Due Diligence Concluded / Commencement of Definitive Agreement

VANCOUVER, BC, Sept. 22, 2025 /CNW/ — Lithium South Development Corporation (the “Company” or “Lithium South”) (TSX-V: LIS) (OTCQB: LISMF) (Frankfurt: OGPQ) ) is providing an update to its news release of July 30, 2025 and August 7, 2025 regarding the sale of the Hombre Muerto North Lithium Project property package to POSCO Argentina SAU, which is the 100-per-cent owned Argentine subsidiary of POSCO Holdings Inc. (“POSCO’), referred to as the Transaction. 

Due Diligence by POSCO Argentina S.A.U.  has now been substantially completed with several minor items remaining outstanding. The parties are now moving forward with the negotiation of the Definitive Agreement. Matters under review prior to the completion of the Transaction include closing costs, legal and accounting costs and potential tax considerations.  

The Company expects to complete this process within the time frame previously announced on August 7, 2025. Once the Definitive Agreement is complete, the Company will provide details about our Annual General and Special Meeting date as well as provide further details on the issuer bid to purchase up to all of the issued and outstanding securities of the Company.

About Lithium South Development Corp.

Lithium South owns 100% of the HMN Li Project located in Salta and Catamarca Provinces, Argentina, in the heart of the lithium triangle. The Salar del Hombre Muerto has a history of lithium production, with Rio Tinto Lithium (Formerly Arcadium Lithium and recently purchased by Rio Tinto Corporation for US$6.7 billion in March 2025) in operation to the south of the HMN Li Project for over twenty-five years.  The HMN Li Project is adjacent to the east with a U.S. billion-dollar lithium development by POSCO Argentina S.A.U., now in lithium production. Exploration work to date has delineated a NI 43-101 compliant 1,583,200 tonne Lithium Carbonate Equivalent (“LCE”) Resource at an average grade of 736 milligrams per liter lithium (mg/L Li ) , with 1,463,000 tonnes in the measured category  and 120,000 tonnes in the indicated category, at a cutoff grade of 500 mg/l Li (Note 1 below) on the Alba Sabrina, Natalia Maria, and Tramo claim blocks, three of five non-contiguous blocks that make up the HMN Li Project (View Report: www.lithiumsouth.com/wp-content/uploads/2023-technical-report-NI43-101.pdf). A recent Preliminary Economic Assessment (Note 2 below) April 30, 2024, delineates potential to develop a 15,600 tonne per year lithium carbonate project.  LIS is now moving the project forward to a Feasibility Study.

On behalf of the Board of Directors

Adrian F. C. Hobkirk

President and Chief Executive Officer

Investors / Shareholders call 855-415-8100 / website: www.lithiumsouth.com

The contents of this press release and the scientific information contained herein were reviewed by Mr. William Feyerabend, CPG, a Consulting Geologist and a Qualified Person under N.I. 43-101. Mr. Feyerabend participated in the writing of this press release and approves the content.

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release. The TSX Venture Exchange has not reviewed the content of this news release and therefore does not accept responsibility or liability for the adequacy or accuracy of the contents of this news release.

Note 1: A report titled, Updated Mineral Resource Estimate – Hombre Muerto North Project, NI 43-101 Technical Report Catamarca and Salta, Argentina, Mark King, PhD, PGeo, Peter Ehren, M.Sc, MAusIMM, September 5th, 2023.

Note 2: The report titled, N.I. 43-101 Preliminary Economic Assessment Hombre Muerto North Lithium Project, Salta, Argentina, was completed by Knight Piesold Consulting and JDS Energy and Mining Inc., and on SEDAR April 30, 2024

This news release contains certain “forward-looking statements” within the meaning of Section 21E of the United States Securities and Exchange Act of 1934, as amended. Except for statements of historical fact relating to the Company, certain information contained herein constitutes forward-looking statements. Forward-looking statements are based upon opinions and estimates of management at the date the statements are made and are subject to a variety of risks and uncertainties and other factors which could cause actual results to differ materially from those projected in the forward-looking statements.  The reader is cautioned not to place undue reliance on forward- looking statements.  We seek safe harbor.

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SOURCE Lithium South Development Corporation