Natural hydrogen firm secures €31m to carry out exploration campaign

French start-up Mantle8 has raised €31m ($36.3m) in Series A funding to finance an exploration and drilling campaign to develop sources of high-purity, low-cost geologic hydrogen.

Led by climate-tech and deep-tech venture capital entities, the funding round will go towards deploying Mantle8’s technology over two years to confirm workable reservoirs, which the firm claims could produce hydrogen at costs as low as €0.80/kg ($0.94).

The company has already applied for “multiple” permits globally and is currently carrying out data acquisition across a 700km² surface area in the south of France.

Mantle8’s technology stack combines geological, geophysical, and geochemical analysis to map subsurface hydrogen-generating systems, migration pathways, and geological traps, to identify and rank viable natural hydrogen prospects.

Bart Markus, Mantle8 Chairman, said the funding round would allow the company to move from exploration to commercial development.

In February 2025, the company raised €3.4m ($4m) in , at the time outlining a target of finding 10 million tonnes of natural hydrogen by 2030 to complement EU goals.

While natural hydrogen could present a high-volume and low-cost pool of the molecule, its availability and practicality remain unproven at large scale.

Questions remain, including around the rate of replenishment versus the rate of extraction, costs of exploratory failure, dilution levels threatening commercialisation, and the carbon intensity of extraction, purification, and compression.

Since the early 2020s, the number of natural hydrogen exploration companies has grown from just a few to over 40.