18 June 2025

Mosman Oil and Gas Limited

("Mosman" or the "Company")

Drilling commenced at The Bard lease, Vecta Project

Mosman Oil and Gas Limited (AIM:MSMN) the helium, hydrogen and hydrocarbon exploration, development and production company, announces an update on the second well in the drilling campaign at the Vecta Project, Colorado, US.

Highlights

·      Drilling has commenced and casing set in the Richardson TH well on "The Bard" lease area. This is the second location in the five-well drilling campaign.

·      The well will test the Lyons Sandstone formation, with a planned total depth (TD) of 725 feet.

·      Gas will be tested at intervals to determine concentrations of any gases encountered while drilling, including helium, and wireline logging may be conducted at TD to determine reservoir and gas/fluid properties.

Vecta Project

The Vecta Project is located mainly in Las Animas County, close to the Red Rocks helium producing field and Blue Star Helium's Galactica development project. Helium concentrations of up to 11% have been encountered in offset wells and fields in the area, with the closest well, Texaco Cynthia True-1, flowing 8.8% helium from the upper Lyons sandstone.

This is the second of five wells planned in this drilling campaign testing five individual structural closures. The first well being drilled on the Billy Goat lease area to the east. Mosman has a 90% working interest in "The Bard" lease area following Vecta's decision to farmout their working interest (RNS 1655N, Vecta project update 17^th June).

Key Terms of Agreement

·      Vecta will continue to operate at no cost to Mosman in return for a 10% carried interest

·      Mosman has the right to take over operatorship of the lease

·      Vecta has the right to buy back into the lease for four times the drilling costs

Location Map illustrating the five prospects identified by surface mapping within the Project Area. (Source: Vecta Oil and Gas Ltd.)

Andy Carroll, Chief Executive Officer of Mosman, said: "The drilling at 'The Bard' lease area of the Vecta project is an exciting opportunity to test a second helium target in an area of proven helium development and production.

"Each well location has been carefully selected by the very experienced team at Vecta with special acknowledgment of the work by the late Matt Goolsby.

"I believe each of these wells has an excellent chance of discovering helium. The low-cost drilling of these wells enables data to be obtained quickly and at very reasonable cost."

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.