Sagebrush Production Update.

18 August 2025

Mosman Oil and Gas Limited

("Mosman" or the "Company")

Sagebrush Production Update

Mosman Oil and Gas Limited (AIM: MSMN), advancing helium, hydrogen and hydrocarbon projects in the USA, is pleased to provide an update on oil production from the Sagebrush Project in Colorado, USA, where the Company holds an 82.5% working interest.

Sagebrush Oil Production - January to June 2025 ( Gross 100%¹ )

Notes: ¹Figures are reported on a 100% project basis and are not adjusted for Mosman's 82.5% working interest.  ² Production represents gross 100% oil volumes but after royalties and certain deductions. All oil sales are unhedged.

The Company will provide further updates on its other projects in due course.

Interim CEO Howard McLaughlin commented "Our core focus remains firmly on advancing Mosman's flagship helium projects at Sagebrush and Coyote Wash, which represent the most significant growth opportunities for the Company. At the same time, oil production from Sagebrush provides material revenues that assist in supporting our wider activities. We are pleased with production so far in 2025, and since June the production numbers have been meeting our expectations and are in line with prior quarters. The independent verification report from Sproule on the Sagebrush helium discovery is advancing well, and we are looking forward to getting the 3D seismic survey underway at Sagebrush. We also expect to hear news regarding the Coyote Wash environmental approval. For both Sagebrush and Coyote Wash, we have an exciting few months ahead as we work towards unlocking the significant helium potential within these projects."

Market Abuse Regulation (MAR) Disclosure

The information contained within this announcement is deemed by the Company to constitute inside information as stipulated under the Market Abuse Regulations (EU) No. 596/2014 ('MAR') which has been incorporated into UK law by the European Union (Withdrawal) Act 2018. Upon the publication of this announcement via Regulatory Information Service ('RIS'), this information is now considered to be in the public domain.

Enquiries:

Updates on the Company's activities are regularly posted on its website: www.mosmanoilandgas.com

Notes to editors

Mosman (AIM: MSMN) is a helium, hydrogen and hydrocarbon exploration, development, and production company with projects in the US and Australia. Mosman's strategic objectives remain consistent: to identify opportunities which will provide operating cash flow and have development upside, in conjunction with progressing exploration. The Company has several projects in the US, in addition to royalty interests in Australia.