Solvay SA — Proxy Solicitation & Information Statement 2026

Apr 9, 2026

In order to be admitted to the Ordinary Shareholder's Meeting on Tuesday 12 May 2026, SOLVAY SA/NV must be in possession of this notice of attendance by Wednesday 6 May 2026 11.59 p.m. at the latest

NOTICE OF ATTENDANCE

I, the undersigned, (name, first name and address to be completed)

Owner of the above-mentioned registered shares, advise the said company of my intention to attend the Ordinary Shareholders' Meeting that will be held on Tuesday 12 May 2026 at 10.30 a.m., at Event Lounge, Boulevard Général Wahis 16/F, 1030 Brussels, with all shares registered under my name at the record date, on Tuesday 28 April 2026 at midnight.

Signed at , on 2026.

Signature(s)

SOLVAY SA/NV must be in possession of this notice of attendance, duly completed and signed, by Wednesday 6 May 2026 11.59 p.m. at the latest.

This document can be sent to Solvay SA/NV,

• either by post to the following address: Solvay SA/NV, Shareholders' Meeting, rue de Ransbeek 310, 1120 Brussels,
• or by e-mail to the following address: ag.solvay@solvay.com.

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To be valid, this proxy must be received by Solvay SA/NV no later than 6 May 2026 11.59 p.m.

PROXY FOR THE ORDINARY SHAREHOLDERS' MEETING OF SOLVAY SA ON 12 MAY 2026

I, the undersigned, (name, first name and address to be completed)

holder of

grant authority to

Name, first name :

Address :

Solvay SA/NV shares, on the record date, set on Tuesday 28 April 2026 at midnight, hereby declares to

or failing that, to Michel Washer (former executive of Solvay SA/NV)

each with the right of substitution,

to represent me at the Ordinary Shareholders' Meeting of Solvay SA/NV that will take place on Tuesday 12 May 2026 at 10.30 a.m. (Belgian time) and to vote in my name on all the items on the agenda.

The proxy holder may also sign all deeds, documents, minutes, attendance lists and other documents relating to the Ordinary Shareholders' Meeting and, in general, do whatever is necessary to fulfill this mandate.

Legal entity shareholders must specify the name(s), first name(s) and capacity of the physical person(s) who sign(s) this proxy form on their behalf. The physical person(s) hereby declare(s) and warrant(s) to Solvay SA/NV to have full authority to execute this proxy form.

Solvay SA/NV must be provided with this proxy, duly completed and signed, by 6 May 2026 11.59 p.m. at the latest. In addition, shareholders must comply with the registration procedure described in the convening notice to the Ordinary Shareholders' Meeting. The proxy may be sent either by mail to the company's registered office: Solvay SA, Shareholders' Meeting, 310 rue de Ransbeek, 1120 Brussels, or by e-mail to ag.solvay@solvay.com.

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Each proxy must provide precise voting instructions for each item on the agenda.

In the absence of indication on how to vote for one or more of the resolutions proposed below or if the instructions as to the meaning of the vote given by the shareholder are not clear, this will constitute an instruction to vote in favour of the relevant proposed resolution(s).

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Ordinary Shareholders' Meeting

1. Management report for the financial year 2025 (including the Corporate Governance Statement)
2. Auditor's report for the financial year 2025
3. Communication of the consolidated accounts for the financial year 2025 – Auditor’s report on the consolidated accounts
4. Approval of the annual accounts for the financial year 2025 – Allocation of profits and determination of the dividend

Proposed resolution: To approve the annual accounts and the allocation of profits for the financial year 2025 and to set the gross dividend per share at EUR 2.43. After deduction of the gross interim dividend of EUR 0.97 per share, paid on 21 January 2026, the balance of the gross dividend amounts to EUR 1.46 per share, payable as from 20 May 2026.

FOR ☐ AGAINST ☐ ABSTAIN ☐

1. Discharge of the directors for the financial year 2025

Proposed resolution: To grant discharge to the directors in office during the financial year 2025 for the performance of their duties during the financial year 2025.

FOR ☐ AGAINST ☐ ABSTAIN ☐

1. Discharge of the auditor for the financial year 2025

Proposed resolution: To grant discharge to the auditor, EY Reviseurs d'Entreprises SRL, represented by Mr. Eric Van Hoof, for the performance of its duties during the financial year 2025.

FOR ☐ AGAINST ☐ ABSTAIN ☐

1. Approval of the remuneration report relating to the financial year 2025

Proposed resolution: To approve the remuneration report relating to the financial year 2025, as included in chapter 6 of the Corporate Governance Statement.

FOR ☐ AGAINST ☐ ABSTAIN ☐

1. Board of Directors: Renewal of mandate of Mr. Pierre Gurdjian as independent director

The mandate of Mr. Pierre Gurdjian, independent director and Chair of the Board, shall expire at the end of this Meeting. The Board of Directors proposes renewing Mr. Gurdjian’s mandate for a period of four years (until the end of the Ordinary Shareholders’ Meeting which will be requested to approve the annual accounts relating to the financial year 2029). If renewed by the Ordinary Shareholders’ Meeting, Mr. Gurdjian will remain Chair of the Board.

Mr. Gurdjian meets the independence criteria stipulated by article 7:87 of the Belgian Code of Companies and Associations, provision 3.5 of the 2020 Corporate Governance Code and by the Solvay Corporate Governance Charter. Pursuant to article 7:87 §1 al.3 of the Belgian Code of Companies and Associations, the Board also expressly confirms that it has no indication of any element that could impair the independence of Mr. Gurdjian in accordance with the above-mentioned criteria.

The curriculum vitae and information on other board mandates of Mr. Gurdjian are available on the website of Solvay (https://www.solvay.com/en/investors/corporate-governance/board-directors).

Proposed resolution: To renew the mandate of Mr. Pierre Gurdjian as independent director for a period of four years, as his current mandate expires at the end of this Meeting. His mandate will expire at the end of the Ordinary Shareholders’ Meeting which will be requested to approve the annual accounts relating to the financial year 2029.

FOR ☐ AGAINST ☐ ABSTAIN ☐

1. Miscellaneous

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In case shareholders, in accordance with Article 7:130 of the Code of Companies and Associations, exercise their right to add items to the agenda and/or to submit resolution proposals with regard to existing agenda items or new items to be added to the agenda, proxies submitted prior to the publication of the revised agenda shall remain valid for the agenda items that they cover. Solvay SA will also make the revised agenda and a revised model of shareholder proxy form available on its website (http://www.solvay.com/en/investors/shareholders-meeting/index.html) at the latest on 27 April 2026, in order to allow shareholders who would wish to give specific voting instructions on the new agenda items and/or new/alternative proposed resolutions.

In case new/alternative proposed resolutions are submitted with respect to agenda items existing after the notified proxies, the proxy holder shall abstain from voting on the new/alternative proposed resolutions. However, in this case, shareholders will have the possibility to send a new proxy to Solvay SA, using the revised proxy form mentioned in the previous paragraph.

PROTECTION OF PERSONAL DATA

Solvay SA is responsible for processing the personal data it receives from shareholders and proxies in the context of the Shareholders' Meeting in accordance with the applicable data protection laws, including the European Regulation 2016/679 of 27 April 2016 on the protection of natural persons with regard to the processing of personal data and on the free movement of such data (GDPR).

This personal data consists mainly of identification data of shareholders, their representatives or proxies, contact data (e.g. postal address, telephone number, e-mail address), number and type of shares, intention to participate, attendance at the Shareholders' Meeting, questions asked, votes cast, etc.

This data will be used to prepare and manage the attendance and voting process for the Shareholders' Meeting, as described in the convening notice, and will be passed on to third parties assisting the company for the above purposes, in particular Lumi. This processing of personal data is necessary in order to meet the legal obligations of Solvay SA. If Solvay SA does not process this personal data, it will not be able to allow the person concerned to be present or to be represented at the Shareholders' Meeting and/or to register the vote as a shareholder of Solvay SA.

This information will not be kept longer than necessary for the same purposes, i.e. 10 years after the Shareholders' Meeting.

For more information, shareholders and proxy holders can consult our "Data Protection and Privacy Policy" via the link https://www.solvay.com/en/information/data-protection-and-privacy-policy.html.

As set out in our Data Protection Policy referred to above, you also have rights with respect to your personal data in accordance with the applicable legal conditions and limits, namely the right of access to your personal data, the rectification or deletion thereof, as well as the right to restrict processing, the right to object to processing, the right to data portability and the right to lodge a complaint with the competent supervisory authority - in Belgium, the Data Protection Authority).

You can exercise your rights mentioned above by contacting the Corporate Secretary of Solvay SA at, Solvay SA, 310, rue de Ransbeek - 1120 Brussels (Belgium) (e-mail: ag.solvay@solvay.com).

Signed at

, on

2026.

Signature

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To be valid, this vote by correspondence form must be received by Solvay SA/NV no later than 6 May 2026 11.59 p.m.

VOTE BY CORRESPONDENCE

I, the undersigned,

Legal entity shareholders must specify the name (s), first name(s) and capacity of the physical person(s) who sign(s) this vote by correspondence form on their behalf. If the undersigned is not a physical person who executes this vote by correspondence form himself/herself, the signatory hereby declares and warrants to Solvay SA/NV to have full authority to execute this vote by correspondence form on behalf of the undersigned.

holder of:
____ registered shares,
____ dematerialised shares,

on the record date, of Solvay SA/NV, with registered office at 310 Rue de Ransbeek, 1120 Brussels,

exercise my voting right in the following way on the items on the agenda of the Solvay SA/NV Ordinary Shareholders' Meeting that will take place on Tuesday 12 May 2026 at 10.30 a.m. (Belgian time) at the Event Lounge, Boulevard Général Wahis 16/F, 1030 Brussels.

This vote is also valid for any Shareholders' Meeting that will be convened with the same agenda, provided that the shareholder complies with the registration and confirmation procedures provided for such Meeting.

Ordinary Shareholders' Meeting

1. Management report for the financial year 2025 (including the Corporate Governance Statement)
2. Auditor's report for the financial year 2025
3. Communication of the consolidated accounts for the financial year 2025 – Auditor's report on the consolidated accounts
4. Approval of the annual accounts for the financial year 2025 – Allocation of profits and determination of the dividend

Proposed resolution: To approve the annual accounts and the allocation of profits for the financial year 2025 and to set the gross dividend per share at EUR 2.43. After deduction of the gross interim dividend of EUR 0.97 per share, paid on 21 January 2026, the balance of the gross dividend amounts to EUR 1.46 per share, payable as from 20 May 2026.

FOR ☐ AGAINST ☐ ABSTAIN ☐

1. Discharge of the directors for the financial year 2025

Proposed resolution: To grant discharge to the directors in office during the financial year 2025 for the performance of their duties during the financial year 2025.

FOR ☐ AGAINST ☐ ABSTAIN ☐

1. Discharge of the auditor for the financial year 2025

Proposed resolution: To grant discharge to the auditor, EY Reviseurs d'Entreprises SRL, represented by Mr. Eric Van Hoof, for the performance of its duties during the financial year 2025.

FOR ☐ AGAINST ☐ ABSTAIN ☐

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1. Approval of the remuneration report relating to the financial year 2025

Proposed resolution: To approve the remuneration report relating to the financial year 2025, as included in chapter 6 of the Corporate Governance Statement.

FOR ☐ AGAINST ☐ ABSTAIN ☐

1. Board of Directors: Renewal of mandate of Mr. Pierre Gurdjian as independent director

The mandate of Mr. Pierre Gurdjian, independent director and Chair of the Board, shall expire at the end of this Meeting. The Board of Directors proposes renewing Mr. Gurdjian’s mandate for a period of four years (until the end of the Ordinary Shareholders’ Meeting which will be requested to approve the annual accounts relating to the financial year 2029). If renewed by the Ordinary Shareholders’ Meeting, Mr. Gurdjian will remain Chair of the Board.

Mr. Gurdjian meets the independence criteria stipulated by article 7:87 of the Belgian Code of Companies and Associations, provision 3.5 of the 2020 Corporate Governance Code and by the Solvay Corporate Governance Charter. Pursuant to article 7:87 §1 al.3 of the Belgian Code of Companies and Associations, the Board also expressly confirms that it has no indication of any element that could impair the independence of Mr. Gurdjian in accordance with the above-mentioned criteria.

The curriculum vitae and information on other board mandates of Mr. Gurdjian are available on the website of Solvay (https://www.solvay.com/en/investors/corporate-governance/board-directors).

Proposed resolution: To renew the mandate of Mr. Pierre Gurdjian as independent director for a period of four years, as his current mandate expires at the end of this Meeting. His mandate will expire at the end of the Ordinary Shareholders’ Meeting which will be requested to approve the annual accounts relating to the financial year 2029.

FOR ☐ AGAINST ☐ ABSTAIN ☐

1. Miscellaneous

Data Protection

Solvay is responsible for the processing of the personal information that it receives from shareholders in the context of the Meeting in accordance with applicable data privacy laws.

Such information will be used for the purposes of analyzing and administrating the attendance and voting process in connection with the Meeting, as set out in this convening notice, and will be transferred to third parties assisting the Company for the above purposes. This information will not be kept longer than necessary for these purposes. Shareholders can consult the “Data Protection and Privacy Policy” with the link https://www.solvay.com/en/information/data-protection-and-privacy-policy.html. They may request access to their data and any additional modification by contacting the Corporate Secretary of Solvay SA at, Solvay SA, 310, rue de Ransbeek - 1120 Brussels (Belgium) (e-mail: ag.solvay@solvay.com).

This form will be considered null and void in its entirety if the shareholder has not indicated above his or her choice concerning one or more items on the agenda of the Shareholders’ Meeting.

Shareholders who have cast their vote by validly returning this form to the company may not vote by proxy at the Shareholders’ Meeting for the number of votes already cast.

Shareholders who wish to vote by correspondence must comply with the practical formalities. Solvay SA must receive this form, duly completed and signed by 6 May 2026 11.59 p.m. at the latest. All practical formalities are set out in the convening notice of the Ordinary Shareholders’ Meeting.

This form can be sent by regular mail to the corporate headquarters: Solvay SA, Assemblée Générale, 310 rue de Ransbeek at 1120 Brussels, or by electronic mail to the e-mail address: ag.solvay@solvay.com. In the case of sending via e-mail, a scanned or photographed copy of the completed and signed form should be sent to the company.

Signed at __, on __, 2026.

Signature

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SOLVAY

SOLVAY SA/NV
RPM 0403091220
ORDINARY SHAREHOLDERS' MEETING
12 May 2026 at 10.30 a.m.
Event Lounge, Boulevard Général Wahis 16/F, 1030 Brussels

EXPLANATORY NOTE

This note is prepared in accordance with Article 7:129 §3, 4° of the Companies and Associations Code and contains an explanation of the meaning of each item on the agenda of the Ordinary Shareholders' Meeting.

For further information concerning the Ordinary Shareholders' Meeting and the applicable formalities, please refer to the convening notice published on the website of Solvay.

1. Management report for the financial year 2025 (including the Corporate Governance Statement)

The Board of Directors has prepared a management report for the financial year 2025, including the Corporate Governance Statement, which contains all the information required by law.

The management report is available on the website of Solvay, has been sent to the registered shareholders and is also available on request.

This item is included for communication purposes only and does not require a resolution to be adopted.

1. Auditor's report for the financial year 2025

The auditor's report is unqualified.

The auditor's report is available on the website of Solvay, has been sent to the registered shareholders and is also available on request.

This item is included for information purposes only and does not require a resolution to be adopted.

1. Communication of the consolidated accounts for the financial year 2025 – Auditor's report on the consolidated accounts

The consolidated accounts for the financial year 2025 have been verified and approved by the Board of Directors. The auditor's report is unqualified.

These documents are available on the website of Solvay and are also available on request.

This item is included for communication purposes only and does not require a resolution to be adopted.

1. Approval of the annual accounts for the financial year 2025 - Allocation of profits and determination of the dividend

It is proposed that the annual accounts for the financial year 2025 be approved, that the profits for the financial year 2025 be appropriated and that the gross dividend per share be set at EUR 2.43, meaning that, after deduction of the gross interim dividend of EUR 0.97 per share paid on 21 January 2026, the balance of the gross dividend will amount to EUR 1.46 per share, payable as from 20 May 2026.

The 2025 annual accounts are available on the website of Solvay, have been sent to the registered shareholders and are also available on request.

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SOLVAY

The Belgian Code of Companies and Associations requires that the Shareholders' Meeting decides each year on the approval of the annual accounts, as well as on the allocation of profits and the determination of the dividend.

1. Discharge of the directors for the financial year 2025

It is proposed to grant discharge to the directors in office during the financial year 2025 for the performance of their duties during the financial year 2025.

In accordance with the Belgian Code of Companies and Associations, the Shareholders' Meeting must decide each year, after approval of the annual accounts, by a special vote on the release from liability of the directors.

1. Discharge of the auditor for the financial year 2025

It is proposed to grant discharge to the auditor, EY Reviseurs d'Entreprises SRL, represented by Mr. Eric Van Hoof, for the performance of its duties during the financial year 2025.

In accordance with the Belgian Code of Companies and Associations, the Shareholders' Meeting must decide, after approval of the annual accounts, by a special vote on the release from liability of the auditor.

1. Approval of the remuneration report relating to the financial year 2025

It is proposed to approve the remuneration report relating to the financial year 2025, as included in chapter 6 of the Corporate Governance Statement.

The report transparently discloses how the remuneration policy that is currently in effect was applied by the Board of Directors.

The Belgian Code of Companies and Associations requires that the Shareholders' Meeting decides each year on the approval of the remuneration report. This report provides information on the remuneration of the members of the Board of Directors and the Executive Leadership Team.

1. Board of Directors: Renewal of mandate of Mr. Pierre Gurdjian as independent director

The mandate of Mr. Pierre Gurdjian, independent director and Chair of the Board, shall expire at the end of this Meeting. The Board of Directors proposes renewing Mr. Gurdjian's mandate for a period of four years (until the end of the Ordinary Shareholders' Meeting which will be requested to approve the annual accounts relating to the financial year 2029). If renewed by the Ordinary Shareholders' Meeting, Mr. Gurdjian will remain Chair of the Board.

Mr. Gurdjian meets the independence criteria stipulated by article 7:87 of the Belgian Code of Companies and Associations, provision 3.5 of the 2020 Corporate Governance Code and by the Solvay Corporate Governance Charter. Pursuant to article 7:87 §1 al.3 of the Belgian Code of Companies and Associations, the Board also expressly confirms that it has no indication of any element that could impair the independence of Mr. Gurdjian in accordance with the above-mentioned criteria.

The curriculum vitae and information on other board mandates of Mr. Gurdjian are available on the website of Solvay (https://www.solvay.com/en/investors/corporate-governance/board-directors).

It is proposed to renew the mandate of Mr. Pierre Gurdjian as independent director for a period of four years, as his current mandate expires at the end of this Meeting. His mandate will expire at the end of the Ordinary Shareholders' Meeting which will be requested to approve the annual accounts relating to the financial year 2029.

1. Miscellaneous