6 June 2025

Mosman Oil and Gas Limited

("Mosman" or the "Company") 

Completion of Sale of EP 145

Mosman Oil and Gas Limited (AIM:MSMN) the helium, hydrogen and hydrocarbon exploration, development and production company, is pleased to announce completion of the Sale and Purchase Agreement (SPA) and Transfer of Title on permit EP 145, Amadeus Basin, NT, Australia to Echelon Resources Limited ("Echelon", ASX:ECH).

Summary

Echelon is a participant in the Mereenie, Palm Valley and Dingo oil and gas fields, and is drilling wells and selling hydrocarbon gas to the NT government. EP-145 is located within Echelon's core asset area in the Amadeus Basin, Northern Territory with robust infrastructure and identified exploration opportunities. Echelon has indicated it plans to acquire high resolution 3D seismic followed by drilling to define the West Walker-1 gas discovery with the aim of tying any development of the gas resource into the Northern Territory gas market. This provides the fastest potential path to production and commercialisation of EP-145.

The acquisition of seismic and drilling of wells will add to the geological understanding of EP-145. Echelon's focus is hydrocarbons and the portion of EP-145 adjacent to the Mereenie gas field. Once Echelon has further defined its area of interest and advised Mosman that it does not wish to extend the exploration licence, Mosman can elect to apply to continue helium exploration in the other parts of EP-145.

Payment from the sale of EP-145 will be used to fund exploration and appraisal activity in Mosman's US assets. This transaction saves Mosman estimated costs of approximately AU$2.5 million that would have been required as part of a Year Three permit work programme commitment.

Further details in respect of the sale of EP-145 were included in the Company's announcement of 14 January 2025.

Andy Carroll, Chief Executive Officer of Mosman, said: "Completion of the sale of EP-145 provides funding to support the ongoing appraisal and exploration at Mosman's priority projects in the US which have proven helium resources, located near existing helium production with access to infrastructure and to markets.

"We are pleased to retain a 5% royalty interest in EP-145's helium potential at no cost to Mosman, with the potential to re-acquire that acreage with the benefit of further exploration activity having been conducted in EP145 in the interim."

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 exploration projects in the Amadeus Basin in Central Australia.

Notification and public disclosure of transactions by persons discharging managerial responsibilities and persons closely associated with them

In accordance with the requirements of the EU Market Abuse Regulation, the Company confirms that it has received notification from Mr. Dumbrell in respect of his appointment as Chairman, and there are no further details to disclose under the AIM Rules.