Retail Offer

Mosman Oil and Gas Limited or the "Company" (AIM:MSMN) the hydrocarbon, helium and hydrogen exploration, development, and production company, is pleased to announce an offer to its existing retail shareholders CMC CapX (the "Retail Offer") of new ordinary shares of NPV each in the capital of the Company (the "Retail Offer Shares").

In addition to the Retail Offer, the Company is also conducting a placing of new ordinary shares (the "Placing Shares" and together with the Retail Offer Shares, the "Fundraising Shares") (the "Placing"). The price of the Fundraising Shares is 0.0225p (the "Issue Price").

A separate announcement has been made regarding the Placing and its terms. For the avoidance of doubt, the Retail Offer is separate from and does not form part of the Placing.

The Retail Offer and the Placing are conditional on, the Fundraising Shares being admitted to trading on the AIM market operated by London Stock Exchange plc ("Admission"). Admission of the Placing Shares is expected to take place at 8.00 a.m. on 23rd October 2025. Admission of the Retail Offer Shares is expected to take place at 8.00 a.m. on 27th October 2025. Completion of the Retail Offer is conditional, inter alia, upon the completion of the Placing.

The Retail Offer

The Company values its retail shareholder base and believes that it is appropriate to provide its existing retail shareholders in the United Kingdom the opportunity to participate in the Retail Offer via participating financial intermediaries.

Therefore, the Company is making the Retail Offer open to Eligible Shareholders (as defined below) in the United Kingdom via CMC CapX following release of this announcement.

To be eligible to participate in the Retail Offer, applicants must be: (i) a retail shareholder of the Company on or prior to the release of this announcement; and (ii) resident in the United Kingdom; and (iii) a customer of a participating intermediary (such persons being "Eligible Shareholders").

The Retail Offer is expected to close by 4pm on 21st October 2025, but the Company reserves the right to close it earlier. Eligible Shareholders should note that financial intermediaries may also have earlier closing times.

Expected timetable

The dates and times specified above are subject to change. In particular, the Company may (with the prior approval of CMC Markets UK plc) bring forward, extend or postpone the closing time and date for the Retail Offer. In the event that a date or time is changed, the Company will notify financial intermediaries who have applied for Retail Offer Shares on behalf of retail investors by post, by electronic mail or by the publication of a notice through a Regulatory Information Service.

Other retail brokers or wealth managers which, in each case, are investment professionals (within the meaning of article 19 of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005), wishing to participate in the Retail Offer on behalf of Eligible Shareholder, should contact CMC CapX via email to capx@cmcmarkets.com or by telephone on +44 (0) 20 3003 8632.

Eligible Shareholders wishing to subscribe for Retail Offer Shares should contact their broker or wealth manager who will confirm if they are participating in the Retail Offer.

There is a minimum subscription of £250 per investor. The terms and conditions on which investors subscribe will be provided by the relevant financial intermediaries including relevant commission or fee charges.

It is vital to note that once an application for Retail Offer Shares has been made and accepted via an intermediary, it is irrevocable and cannot be withdrawn.

The Retail Offer Shares will, when issued, be credited as fully paid and will rank pari passu in all respects with existing ordinary shares in the capital of the Company ("Ordinary Shares") including the right to receive all dividends and other distributions declared, made or paid after their date of issue.

The Retail Offer is not being made into any jurisdiction other than the United Kingdom.

No offering document, prospectus or admission document has been or will be prepared or submitted to be approved by the FCA (or any other authority) in relation to the Retail Offer and investors' commitments will be made solely on the basis of the information contained in this announcement and information that has been published by or on behalf of the Company prior to the date of this announcement by notification to a Regulatory Information Service in accordance with the Disclosure Guidance and Transparency Rules, the AIM Rules for Companies, the Market Abuse Regulation (EU Regulation No. 596/2014) as it forms part of United Kingdom law by virtue of EUWA.

UK Product Governance Requirements

EU Product Governance Requirements

Solely for the purposes of the product governance requirements contained within: (a) EU Directive 2014/65/EU on markets in financial instruments, as amended ("MiFID II"); (b) Articles 9 and 10 of Commission Delegated Directive (EU) 2017/593 supplementing MiFID II; and (c) local implementing measures (together, the "MiFID II Product Governance Requirements"), and disclaiming all and any liability, whether arising in tort, contract or otherwise, which any "manufacturer" (for the purposes of the MiFID II Product Governance Requirements) may otherwise have with respect thereto, the Retail Offer Shares have been subject to a product approval process, which has determined that the Retail Offer Shares are: (i) compatible with an end target market of retail investors and investors who meet the afor distribution through all distribution channels as are permitted by MiFID II (the "EU Target Market Assessment"). Notwithstanding the EU Target Market Assessment, distributors should note that: the price of the Retail Offer Shares may decline and investors could lose all or part of their investment; the Retail Offer Shares offer no guaranteed income and no capital protection; and an investment in the Retail Offer Shares is compatible only with investors who do not need a guaranteed income or capital protection, who (either alone or in conjunction with an appropriate financial or other adviser) are capable of evaluating the merits and risks of such an investment and who have sufficient resources to be able to bear any losses that may result therefrom. The EU Target Market Assessment is without prejudice to the requirements of any contractual, legal or regulatory selling restrictions in relation to the Retail Offer.