Mantle8, a Grenoble-based natural hydrogen exploration startup, has raised €31 million in a Series A round led by Sandwater, with participation from Breakthrough Energy Ventures, the Ecotechnologies 2 fund managed by Bpifrance on behalf of the French government, IP Group, Wind Capital, and Calderion.
The company said the funding will be used over the next two years to run a global exploration and drilling campaign aimed at identifying and testing commercially exploitable reservoirs of high-purity natural hydrogen. The plan includes ranking exploration targets, drilling to confirm hydrogen accumulations, and evaluating reservoir volume, purity, and quality for large-scale production.
Mantle8 develops subsurface modelling and exploration technology for natural hydrogen, including its HOREX platform, which produces 4D images of active underground hydrogen systems. The Series A follows a €3.4 million seed round in 2025 and a €2.06 million grant from the EU Just Transition Fund earlier in 2026, bringing the company’s total funding to €37 million.
The company said the funding will be used over the next two years to run a global exploration and drilling campaign aimed at identifying and testing commercially exploitable reservoirs of high-purity natural hydrogen. The plan includes ranking exploration targets, drilling to confirm hydrogen accumulations, and evaluating reservoir volume, purity, and quality for large-scale production.
Mantle8 develops subsurface modelling and exploration technology for natural hydrogen, including its HOREX platform, which produces 4D images of active underground hydrogen systems. The Series A follows a €3.4 million seed round in 2025 and a €2.06 million grant from the EU Just Transition Fund earlier in 2026, bringing the company’s total funding to €37 million.