Rain City Resources Inc. Announces Formal Evaluation Framework with YLB in Bolivia

Agreement advances Rain City's next-generation DLE platform in the Uyuni basin and Bolivia's broader salar ecosystem, one of the world's most strategically important and chemically complex lithium environments

Calgary, May 12, 2026 - Rain City Resources Inc. (CSE: RAIN) ("Rain City" or the "Company") is pleased to announce that it has entered into a Memorandum of Understanding ("MOU") with Yacimientos de Litio Bolivianos ("YLB"), Bolivia's state lithium company, establishing a formal framework for the evaluation of Bolivian brines and laboratory-scale research related to the Company's next-generation Direct Lithium Extraction ("DLE") platform. This MoU represents the first public MoU for lithium executed between YLB and a foreign company in the new Bolivian Administration.

For Rain City, this represents a meaningful strategic step into one of the world's most important lithium resource bases. Bolivia's salar systems - led by the strategic importance of Uyuni and supported by key operating infrastructure in Llipi and La Palca, Potosí - are globally significant not only because of scale, but also because of the complexity of their brine chemistry. This makes process adaptability, metallurgical understanding and disciplined technical evaluation especially important.

Under the MOU, the parties will advance a structured research process that includes a formal proposal, technical coordination, periodic reporting and a joint Technical Coordination Commission to oversee progress and evaluation. The agreement provides Rain City with a credible institutional pathway to assess its DLE platform under real Bolivian conditions within a state-backed framework.

While the MOU does not grant concession rights, resource ownership or a commercial production agreement, Rain City believes that formal entry into technical evaluation in Bolivia is a significant milestone, particularly given the strategic relevance of the Uyuni basin and the broader Bolivian salar ecosystem to the long-term future of the lithium industry.

Benjamin Hill, CEO of Rain City, commented, "This is a significant milestone for Rain City. Bolivia represents one of the most important lithium resource opportunities in the world, and entering a formal evaluation process there is a meaningful step for our company and our technology. Brines associated with Bolivia's major salar systems, including the Uyuni basin, are among the most complex in the world, so participation in this framework carries real validation and long-term strategic value. With this as a focus, we have been successfully working with our new partners, Ion Source to ensure that our hydrodynamic cavitation-electrolysis technology is able to commercially address the extraction of the high magnesium concentration found in South American salars and especially those in Bolivia."

Sebastian Quiñones, Head of Rain LATAM and Board Advisor of Rain City, stated, "From a technical and metallurgical perspective, this is a very important advancement. Bolivia is relevant not only for the scale of its resources, but also for the complexity of its brine chemistry and the strategic importance of its development model. To be in formal evaluation with the state lithium company is highly significant. It allows Rain to demonstrate our intent, technical capability and a long-term sovereign partnership commitment in one of the most important lithium ecosystems in the world."

This development further strengthens Rain's regional platform across the Lithium Triangle and supports the advancement of extraction technologies designed with very low or near-zero water consumption for use in complex brine systems.

About Rain City Resources Inc.

Rain City Resources Inc. is a Canadian public company focused on advancing next-generation Direct Lithium Extraction technologies and building strategic development pathways across the Lithium Triangle and other high-potential jurisdictions. The Company is committed to supporting more efficient, scalable and sustainable lithium production through technical innovation, disciplined execution and regional partnerships.

Cautionary Note Regarding Forward-Looking Information

This release includes certain statements and information that may constitute forward-looking information within the meaning of applicable Canadian securities laws. Forward-looking statements relate to future events or future performance and reflect the expectations or beliefs of management of the Company regarding future events. Generally, forward-looking statements and information can be identified by the use of forward-looking terminology such as "intends", "expects", "anticipates", "plans" or variations of such words and phrases or statements that certain actions, events or results "may", "could", "should", "would" or "occur". This information and these statements, referred to herein as "forward-looking statements", are not historical facts, are made as of the date of this news release and include without limitation, statements regarding: the Company's proposed financing plans; management's expectations regarding future operations, business development initiatives and strategic plans; and discussions of future plans, estimates, forecasts and statements as to management's expectations and intentions.

These forward-looking statements involve numerous risks and uncertainties and actual results might differ materially from results suggested in any forward-looking statements. These risks and uncertainties include, among other things: the Company being unable to execute its business plans as intended; the Company being unable to secure adequate financing; recent market volatility; changes in general economic, financial, market and business conditions; and the state of the financial markets for the Company's securities.

Although management of the Company has attempted to identify important factors that could cause actual results to differ materially from those contained in forward-looking statements or forward-looking information, there may be other factors that cause results not to be as anticipated, estimated or intended. There can be no assurance that such statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements and forward-looking information. Readers are cautioned that reliance on such information may not be appropriate for other purposes. The Company does not undertake to update any forward-looking statement, forward-looking information or financial outlook that are incorporated by reference herein, except in accordance with applicable securities laws.

Neither the Canadian Securities Exchange nor its Regulation Service Provider (as such term is defined in the policies of the Canadian Securities Exchange) accepts responsibility for the adequacy or accuracy of this news release.

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