Schedule One Update - Mendell Helium PLC

COMPANY REGISTERED OFFICE ADDRESS AND IF DIFFERENT, COMPANY TRADING ADDRESS (INCLUDING POSTCODES):

Registered office address: Arran House, Arran Road, Perth, PH1 3DZ Trading address: 1040 E. US Hwy 40 Bypass, Hays, KS 67601, USA

COUNTRY OF INCORPORATION:

Scotland

COMPANY WEBSITE ADDRESS CONTAINING ALL INFORMATION REQUIRED BY AIM RULE 26:

Mendell Helium plc (company number SC680788) is a helium production and exploration company which operates through its wholly owned subsidiary M3 Helium Corp. ("M3 Helium") in Kansas, USA. On 18 May 2026, Mendell acquired the entire issued share capital of M3 Helium. M3 Helium was incorporated to pursue helium production opportunities. It has interests in twelve wells, of which six (Rost 1-26, Peyton 21-1, Nilson 1 Unit 2-22, Smith, Bearman "A"1 and Dimmitt 1) are in production. During 2025 M3 Helium re-completed the Rost 1-26 well ("Rost 1") in Fort Dodge, Kansas. With a recorded flow rate of 250 Mcf/day and a helium composition of 5.1 per cent. within the gas stream, M3 Helium has more recently drilled a twin well 330 feet from Rost 1 - the Rost 2-26 well ("Rost Twin"). The production zone that M3 Helium is targeting in Fort Dodge is known locally as the Morrow Sands, both a narrow and thin formation around 5,000 feet from surface. The management team have carried out considerable work in mapping out the Morrow Sands in Fort Dodge and both existing and future leases of land are typically small tranches designed to access this formation. Based on its experience at Rost 1 and supported by data from analogous wells in Oklahoma, the management team believes that the prospectivity of this region may represent a potentially significant opportunity for the Company. On 30 April 2026, the Company raised gross proceeds of approximately £5 million, the net proceeds of which are intended to be used to roll out a development of helium production zones in the Fort Dodge region through a combination of re-completing existing third party wells and leasing additional land in Fort Dodge to continue to develop opportunities for new production wells.

Number of ordinary shares on Admission: 340,761,938 ordinary shares of £0.01 each in the capital of the Company ("Ordinary Shares"). No new Ordinary Shares are being issued or allotted in conjunction with admission to trading on AIM. Each Ordinary Share carries one vote and the right to dividends. There are no restrictions as to the transfer of the Ordinary Shares. No Ordinary Shares will be held as treasury shares on Admission.

Capital to be raised on admission: N/A Anticipated market capitalisation on Admission: approximately £15 million

PERCENTAGE OF AIM SECURITIES NOT IN PUBLIC HANDS AT ADMISSION :

Approximately 26%

The Company is currently admitted to trading on the Access Segment of the Aquis Stock Exchange Aquis Growth Market.

THE COMPANY HAS APPLIED FOR THE VOLUNTARY CARBON MARKET DESIGNATION (Y/N)

N

Eric James Boyle - Non-Executive Chairman Nicholas (" Nick ") George Selby Tulloch - Chief Executive Officer Paul Ethan Mendell - Chief Technical Officer John Davies Brown - Non-Executive Director

Name % of the issued share capital on Admission Premier Miton 15.55% Paul Mendell 9.30% Invexo LLC 8.97%

NAMES OF ALL PERSONS TO BE DISCLOSED IN ACCORDANCE WITH SCHEDULE 2, PARAGRAPH (H) OF THE AIM RULES:

N/A

• 31 March (ii) Unaudited interim results to 31 December 2025 (M3 Helium), unaudited interim results to 30 September 2025 (Mendell Helium) (iii) 30 September 2026, 31 December 2026, 30 September 2027

EXPECTED ADMISSION DATE:

NAME AND ADDRESS OF NOMINATED ADVISER:

Cairn Financial Advisers LLP 9 th Floor, 107 Cheapside, London, EC2V 6DN United Kingdom

NAME AND ADDRESS OF BROKER:

AlbR Capital Limited 80 Cheapside London EC2V 6EE SI Capital Ltd 20 North Audley Street London, W1K 6WE OAK Securities (a trading name of Merlin Partners LLP) 90 Jermyn Street London SW1Y 6JD Fortified Securities (a trading name of Riverfort Global Capital Ltd) 128 Buckingham Palace Road London SW1W 9SA

A copy of the Admission Document will contain full details about the applicant and the admission of its securities, and will be available from the Company's website at: https://mendellhelium.com/ from Admission.

THE CORPORATE GOVERNANCE CODE THE APPLICANT HAS DECIDED TO APPLY

QCA Corporate Governance Code

DATE OF NOTIFICATION:

NEW/ UPDATE:

Update