Mantle8 appoints HR Director and expands in Grenoble to support global talent strategy
Grenoble, France | 17 February 2026 – Mantle8, the deep-tech geoscience company pioneering natural hydrogen exploration, has strengthened its leadership team with the appointment of a Human Resources Director and the opening of a new office in Grenoble.
Mantle8 today announced the appointment of Laurence Tiberghien-Portaz as Human Resources Director, further reinforcing its leadership team as the company enters its next phase of development. She joins following the recent appointment of Sylvain Marcant as Chief Commercial Officer.
Laurence Tiberghien-Portaz will be responsible for defining and implementing Mantle8’s human resources strategy, supporting organisational growth, talent development and operational scale-up. She brings extensive experience from the global mining sector, notably with Rio Tinto, where she worked in complex, international environments that demand the integration of advanced geoscience, industrial execution and multicultural teams. Her background aligns closely with Mantle8’s ambition to attract the very best talent worldwide and build a globally recognised centre of excellence in natural hydrogen exploration.
Emmanuel Massini, CEO of Mantle8, said:
These appointments reflect our transition into a new stage of the company’s development,
“As Mantle8 moves from validation to execution, building a strong leadership team and a structured organisation is essential. Laurence brings the experience and global perspective needed to support this transformation.”
Her appointment reflects Mantle8’s deliberate focus on assembling a world-leading, international scientific team capable of unlocking a new natural resource. Today, the company brings together employees from nine nationalities, spanning an age range of 22 to 60, combining early-career researchers with decades of field expertise. Women currently represent 35% of the workforce, with a target of reaching 50% by the end of 2027. Around 80% of employees hold PhDs in geoscience or related disciplines, underscoring Mantle8’s identity as a science-driven exploration company.
These leadership appointments coincide with Mantle8’s relocation to a new office in Grenoble, reinforcing the company’s presence in one of Europe’s most concentrated deeptech ecosystems.
Situated in the heart of the Alps, Grenoble offers a unique geological setting long associated with major advances in mountain formation, glaciology and geophysics, effectively providing a natural laboratory aligned with Mantle8’s subsurface exploration mission. The city also hosts a dense network of research and engineering institutions, including CEA Grenoble, CNRS, Grenoble INP, Université Grenoble Alpes and the GIANT innovation campus, creating an exceptional environment for collaboration and innovation. Combined with its strong international community and outstanding quality of life, Grenoble is a powerful attractor for global scientific talent and an ideal base from which Mantle8 can scale a mission-driven company at the frontier of climate and earth technologies.
The appointment comes as Mantle8 transitions from exploration validation to broader market engagement, following the successful imaging of complete hydrogen-generating systems using its proprietary HOREX technology. After producing the world’s first 4D images of an active natural hydrogen system, the company has established a repeatable and cost-effective framework for exploration. With global interest in natural hydrogen accelerating, Mantle8 is now focused on building the organisational, commercial and industrial capabilities required to support market deployment.
Laurence Tiberghien-Portaz, said:
I’m delighted to be joining Mantle8 at this pivotal moment,
“The company is moving from proof to scale, and my role will be to ensure that the organisation, culture and talent structure are aligned with its long-term ambitions.”
Mantle8 holds multiple exploration permits near demand centres and is positioning itself to contribute to Europe’s evolving approach to clean molecules, energy sovereignty and long-term industrial competitiveness.
With the reinforcement of its executive team and the opening of its new Grenoble office, Mantle8 is laying the foundations for the next chapter in the development of natural hydrogen.
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Mantle8 appoints HR Director and expands in Grenoble to support global talent strategy
