8 October 2026

CleanTech Lithium PLC (“CTL”, CleanTech Lithium” or the “Company”)

New Antofalla Project in Argentina Boosts Plan For Lithium District

CleanTech Lithium PLC (AIM: CTL, Frankfurt:T2N) an exploration and development company advancing sustainable lithium projects, is pleased to announce it has secured promising mining properties located in the southern part of the Salar de Antofalla (the “Antofalla Project” or the “Project”), a major salar in Argentina which is only 80km from CTL’s flagship project, Laguna Verde. While the focus remains on progressing the advanced Laguna Verde Project, the addition of this project enhances CTL’s district scale exploration and development strategy.

Key Highlights:

• Execution of Option Agreements to acquire 100% of two mining properties, Genoveva and Sal de Litio 1, on the Salar de Antofalla in Argentina.
• The mining properties are adjacent to a major exploration project of Albemarle, the world’s largest lithium producer, where their total resource estimate corresponds to 9.5 million tonnes of Lithium Carbonate Equivalent (LCE), with a Measured + Indicated lithium grade of 406 mg/L*
• CleanTech Lithium CEO Ignacio Mehech in his previous role as Vice President of External Affairs for LATAM for Albemarle, had direct involvement in Albemarle’s project from 2021 to early 2024.
• Existing geophysical survey on the Genoveva property within the Antofalla Project suggests a >500 m thick brine aquifer.
• The next step will be to plan and undertake a drill programme which is estimated to cost around US$500,000, targeting a maiden resource estimate for the Project during 2027, subject to available funds.
• The Company will make a schedule of payments as part of the Option Agreements. Over the first year, payments totalling US$525,000 will be made and further payments totalling US$1,400,000 are due in a period from October 2027 to May 2031.
• Funding for the Option Agreement payments for the first year will be covered from existing cash resources.

Ignacio Mehech, Chief Executive Officer of CleanTech Lithium PLC, said: “We are excited by the addition of this project in Argentina. Salar de Antofalla is the largest undeveloped Salar in Argentina, and is strategically located very close to our flagship Laguna Verde Project, as well as to Viento Andino. We expect these three projects to have significant development synergies, as well as potentially benefitting from sharing a centralized conversion facility in Copiapó. The Laguna Verde Project remains  our main focus, however the addition of the Antofalla Project provides strong long term value enhancement for our shareholders.”

Further Details:

Project Overview

Salar de Antofalla is located in Catamarca Province, Argentina, at an altitude of approximately 3,350 m and is accessible by existing roads. Catamarca Province has an active lithium production and development sector.  This includes the Fenix Project, held by Rio Tinto, that has been in production since 1997, and new production bases at the Sal de Vida Project (Rio Tinto) and Tres Quebradas (Zijin Mining). Salar de Antofalla is a major salar with a total area of 540 km2 within a very large basin of 14,500 km2. The salar is over 100 km from north to south with published exploration results indicating that the southern section of the salar has considerably higher lithium grades than the northern portion.

CleanTech Lithium has entered into Option Agreements over two mining properties directly adjacent to an exploration project held by Albemarle in the southern section of the salar. Albemarle´s project, as reported in their 2025 annual report SEC filing (https://s201.q4cdn.com/960975307/files/doc_financials/2025/ar/4fa9927a-565b-49d2-be16-b9d891af459d.pdf) has a total resource estimate of 1.79 million tonnes of lithium which corresponds to 9.5 million tonnes LCE, including a Measured and Indicated resource of 4.8 million tonnes of LCE and corresponding lithium grade of 406 mg/L*. Salar de Antofalla is located within 80 km of Laguna Verde, with existing and planned roads in the region connecting the project to the San Francisco border crossing, where a paved international highway intersects the Laguna Verde Project immediately to the west and passes through to the mining centre of Copiapó and coastal ports. This provides strong potential synergies for development with the Laguna Verde and Viento Andino projects.

Fig. 1: Properties Subject to Option Agreements    Fig. 2: Vicinity to the Laguna Verde Project

Vertical electrical sounding (VES) geophysics was completed on the Genoveva property by the current owner, as shown in Figure 3. Of the two lines completed, the east-west profile of Line 1 is shown in Figure 4, indicating a highly conductive (low resistivity) zone from near surface to the depth extent of the profile at 600 m, providing a vertically and horizontally extensive brine exploration target in that licence area.  As an adjacent area to a major established resource, CTL´s technical team considers that the licences have good potential, justifying further exploration.

Fig 4: VES Line 1: East-West. This figure shows resistivity (ohm-m), where lower values are commonly associated with the presence of brine-saturated sediments in salar environments.

*Information on Albermarle’s resource estimate for its exploration project in Argentina has been taken from Albermarle’s annual accounts 2025 SEC filing, page 36 (https://s201.q4cdn.com/960975307/files/doc_financials/2025/ar/4fa9927a-565b-49d2-be16-b9d891af459d.pdf) which as stated, was prepared by a QP. The resource estimate from Albermarle’s SEC filing has been converted to LCE using the following conversion: lithium mass x 5.323.

Option Agreements

On 6 October 2026 CTL through its wholly owned subsidiary, CleanTech Lithium Ltd (“CTL Ltd.”), executed two Option Agreements to acquire 100% of the two mining properties, Genoveva and Sal de Litio 1 in Argentina. Due diligence on the properties was completed by Beretta Godoy, a leading law firm in the natural resources sector in Argentina. The mining licences comprising the properties are perpetual as long as their good standing requirements are complied with.  The schedule of payments based on the effective date of October 6, 2026, is provided in Table 1 below. The Genoveva licence has a higher cost based on historical work completed. The costs profile is commensurate with the development schedule for the project and in the Board´s view provides a value accretive opportunity for the Company.

Pursuant to the Option Agreements,  CTL Ltd. has the irrevocable and exclusive option to acquire the ownership of the Properties. To maintain the Option in force, CTL Ltd. must continue to make the payments as set out below. Upon making all the Options payments CTL Ltd. will need to notify the current owners in writing of the exercise of the Options. Upon CTL Ltd.’s exercise of the Options, owners will transfer to the entity nominated by CTL Ltd. the ownership of 100% of the Properties.

Table 1: Mining Property Payments as per the Option Agreements (in US$)

Next Steps

The Company intends to undertake a resource evaluation programme at the properties at some point in 2027, subject to available funding estimated cost approximately US$500,000 with the aim of establishing a maiden JORC-compliant resource estimate as a first milestone. The permitting for a drill programme in Argentina takes approximately six months. Due to the elevation of Salar de Antofalla, year round exploration is possible.

Qualified Person Statement

The technical information contained in this disclosure has been reviewed by Mr. Brandon Schneider. Mr. Schneider is employed as a Senior Hydrogeologist at Montgomery & Associates. He graduated from California Lutheran University in 2011 with a Bachelor of Science degree in Geology (with Honors) and obtained a Master of Science in Geological Sciences (Hydrogeology focus) from the University of Notre Dame in 2013. He is a professional in the discipline of Hydrogeology, and is a Registered Professional Geologist in Arizona (#61267) and SME Registered Member (#4306449). He has practiced his profession continuously since 2013. His relevant experience includes: (i) from 2013 to 2016, consulting hydrogeologist specializing in hydrogeological characterizations, aquifer test analyses, groundwater modeling, and pumping well optimization for mining projects and sedimentary basins in Arizona, United States; (ii) since 2017, consulting hydrogeologist in Chile specializing in lithium brine projects in Argentina and Chile with relevant and continuous experience in brine exploration, lithium brine resource and reserve estimates, variable density flow and solute transport modeling, and optimization of groundwater pumping.

Beaumont Cornish Limited ("Beaumont Cornish") is the Company's Nominated Adviser and is authorised and regulated by the FCA. Beaumont Cornish's responsibilities as the Company's Nominated Adviser, including a responsibility to advise and guide the Company on its responsibilities under the AIM Rules for Companies and AIM Rules for Nominated Advisers, are owed solely to the London Stock Exchange. Beaumont Cornish is not acting for and will not be responsible to any other persons for providing protections afforded to customers of Beaumont Cornish nor for advising them in relation to the proposed arrangements described in this announcement or any matter referred to in it. Distribution: This announcement has been notified via a Regulatory Information Service and it is not authorised for distribution into North America or any other jurisdiction where to do so would constitute a violation of the relevant laws or regulations of that jurisdiction.

Notes

About CleanTech Lithium

CleanTech Lithium (AIM:CTL, Frankfurt:T2N) is an exploration and development company advancing lithium projects in Chile for the clean energy transition. CleanTech Lithium has two key lithium projects in Chile, Laguna Verde and Viento Andino, and exploration stage project in Arenas Blancas (Salar de Atacama), located in the lithium triangle, a leading centre for battery grade lithium production. CleanTech Lithium and the Mining Ministry in Chile have agreed the contractual terms for the Special Lithium Operating Contract (“CEOL”) for Laguna Verde, subject to final ratification.

CleanTech Lithium is committed to utilising Direct Lithium Extraction ("DLE") with reinjection of spent brine. Direct Lithium Extraction is a transformative technology which removes lithium from brine with higher recoveries, short development lead times and no extensive evaporation pond construction. For more information, please visit: www.ctlithium.com

**ENDS**