Mantle8 has raised €31 million in Series A funding to advance its proprietary technology platform and launch a global exploration and drilling campaign aimed at identifying the first commercially exploitable reservoir of high-purity natural hydrogen.
The funding round was led by Sandwater and included participation from Breakthrough Energy Ventures, Bpifrance through the Ecotechnologies 2 fund managed on behalf of the French government, IP Group, Wind Capital, and Calderion.
The Grenoble, France-based company said the capital will be used over the next two years to fund what it describes as the world’s most advanced natural hydrogen exploration and drilling campaign. Mantle8’s technology stack is designed to identify commercially viable natural hydrogen reservoirs across its global development pipeline. The company plans to drill selected sites to confirm hydrogen accumulations and assess reservoir quality, purity, and production potential.
Mantle8 said its technology aims to reduce exploration risk and costs associated with natural hydrogen discovery. The company projects potential production costs as low as €0.80 per kilogram, which it believes could significantly reduce the cost of clean hydrogen supply and support Europe’s energy sovereignty objectives.
The Series A round follows a period of growth for the company. In 2025, Mantle8 raised a €3.4 million seed round led by Breakthrough Energy Ventures and completed what it said was the world’s first 4D imaging of an active underground natural hydrogen system using its HOREX® technology at the Hydrogeco project in the French Pyrenees. Earlier in 2026, the company also received a €2.06 million grant from the EU Just Transition Fund to industrialize its exploration technologies.
The latest financing brings Mantle8’s total funding to €37 million, or approximately $44 million.
KEY QUOTES:
“This raise reflects the growing conviction among leading clean tech investors that natural hydrogen is a resource worth pursuing at scale. The existence of natural hydrogen is a well-established scientific fact; the challenge has been finding free gas accumulations of high-purity hydrogen that are commercially viable. I’m proud that we’ve built and patented an entire technology stack to answer this critical challenge, meeting the expectations of our existing shareholders. The next steps are to identify the prospects in our pipeline that meet our commercial hurdles and drill them. I’m excited to welcome investors who have a long history of involvement in subsurface resources, sovereign investments and ecosystem building.”
Emmanuel Masini, Founder and CEO, Mantle8
“We built Sandwater to back exceptional founder teams with the technical depth and operational rigour to solve critical challenges and deliver solutions that lead to a better future. Mantle8 is exactly that kind of company. Emmanuel and his team have built truly proprietary exploration technology, validated it in the field, and now have a clear plan to move into the commercial phase. Natural hydrogen sits at the intersection of energy transition and resource discovery, two areas where Europe must lead as it seeks energy sovereignty. This is a demanding challenge but with the potential to create a new clean energy source, which is what we need and why we see in Mantle8 the opportunity for outsized impact and return.”
Tom Even Mortensen, Founder And Managing Partner, Sandwater
“Geologic hydrogen is one of the most surprising energy developments of the past decade, with the potential to play a significant role in the global energy mix. The Mantle8 team has made impressive progress in advancing its rigorous, geology-driven approach to exploration, and the team continues to execute on targeting the first commercially exploitable reservoir of high-purity natural hydrogen.”
Carmichael Roberts, Breakthrough Energy Ventures
“Natural hydrogen represents a strategic opportunity for France and for Europe. Mantle8 combines a proprietary exploration technology stack with a clear path to commercialization. Backing this company, aligns with our mandate to accelerate the energy transition through sovereign, low-carbon solutions that could be developed before the end of the decade.”
Alexandre Wagner, Investment Director, Bpifrance Green Venture
“With this backing, we will work alongside industrial partners globally to move from exploration through to commercial development. The next two years are about proving that the active hydrogen systems our technology has pinpointed can deliver sustained, commercially viable flow.”
Bart Markus, Chairman, Mantle8
