Job description
🎯 Your mission
As an HR Intern at Mantle8, you will play a key role in structuring and operating our HR function in a fast-scaling environment.
This is not a “classic HR internship”.
👉 You will contribute both to:
- building solid HR foundations
- and ensuring the day-to-day HR operations run smoothly
🧩 What you will do
1. HR structuring & digitalization
Improve and structure our HRIS (Lucca)
Organize HR documentation and workflows
Contribute to the digitalization of HR processes
Create clear and useful internal guides for employees
2. Employee experience & HR content
Support onboarding processes
Help formalize internal policies (working time, remote work, leave…)
Contribute to our internal HR knowledge base (“Bedrock”)
3. HR Operations & People administration (core part of the role)
You will act as a true operational HR partner, at the heart of our daily activity:
Employee lifecycle management
Draft and follow-up contracts, amendments, and HR documents
Manage administrative files
Payroll coordination (France)
Prepare monthly variable payroll elements (EVP)
Interface with our external payroll provider
Ensure data accuracy and reliability
International HR coordination (remote employees)
Work with foreign partners (UK, Germany, Sweden…) for payroll & admin
Support cross-border HR structuring
Gain exposure to international HR practices
Interns & trainees administration
Manage internship agreements
Coordinate with schools and institutions
👉 You will gain a 360° understanding of HR operations, in both French and international contexts
4. A real HR relay
Take ownership of topics with increasing autonomy
Interact with employees and external partners
Actively contribute to structuring the HR function
👉 You are not here to “assist”
👉 You are here to make things work
Profile required
👤 About you
We are looking for someone who is:
- Curious, structured and proactive
- Comfortable with digital tools and eager to optimize processes
- Fluent in English (daily working language)
- Fluent in French to work in French (HR documentation & compliance)
And who is interested in:
- HR structuring & digitalization
- fast-growing environments
- meaningful, science-driven projects
🌟 Why join us?
- Work on real HR topics with real impact
- Gain exposure to international HR operations
- Be part of a fast-growing deeptech startup
- Contribute to an energy transition project
- Join a diverse, collaborative and science-driven team
- Work in Grenoble, at the heart of the Alps 🏔️
✨ Final note
This internship is a unique opportunity to develop a dual skillset:
👉 structuring HR foundations
👉 and running day-to-day HR operations
Company description
🇬🇧 Mantle8 is a deep-tech exploration company dedicated to unlocking the potential of natural hydrogen as a new clean energy resource.
By combining advanced geoscience, subsurface modeling and cutting-edge simulation technologies, Mantle8 develops innovative exploration methods to identify and evaluate natural hydrogen systems deep within the Earth.
Our multidisciplinary team brings together geoscientists, engineers, data scientists and explorers who share a common ambition: advancing scientific understanding while building the foundations of a new energy frontier.
From regional exploration concepts to prospect generation and technological development, Mantle8 works at the intersection of research, innovation and industrial application to accelerate the emergence of natural hydrogen as part of the global energy transition.
At Mantle8, exploration is not only about discovering new resources — it is about expanding knowledge, challenging assumptions and building solutions for the future of energy.
Why is everything in English if Mantle8 is based in the heart of the French Alps?
Because Mantle8 is an international adventure.
As of March 2026, our team includes 21 people representing 9 different nationalities. This diversity is one of our greatest strengths, and English is the language that allows everyone to collaborate, debate ideas and build things together.
We love our home in the French Alps, but inside Mantle8 our common ground is English — from meetings and technical discussions to emails and, yes, even our jokes.
So if you’re thinking about joining us, English is not just helpful — it’s essential to be part of the conversation.
🇫🇷 À propos de Mantle8
Mantle8 est une entreprise deep-tech d’exploration dédiée à révéler le potentiel de l’hydrogène naturel comme nouvelle ressource d’énergie propre.
En combinant géosciences avancées, modélisation du sous-sol et technologies de simulation de pointe, Mantle8 développe des méthodes d’exploration innovantes permettant d’identifier et d’évaluer les systèmes d’hydrogène naturel présents en profondeur dans la Terre.
Notre équipe pluridisciplinaire réunit géoscientifiques, ingénieurs, data scientists et explorateurs partageant une ambition commune : faire progresser la connaissance scientifique tout en construisant les bases d’une nouvelle frontière énergétique.
De la génération de concepts d’exploration régionaux à l’identification de prospects et au développement technologique, Mantle8 opère à l’interface entre recherche, innovation et application industrielle afin d’accélérer l’émergence de l’hydrogène naturel dans la transition énergétique mondiale.
Chez Mantle8, l’exploration ne consiste pas seulement à découvrir de nouvelles ressources — il s’agit aussi d’élargir la connaissance, de remettre en question les certitudes et de construire des solutions pour l’énergie de demain.
Pourquoi tout est-il en anglais alors que Mantle8 est basée au cœur des Alpes françaises ?
Parce que Mantle8 est avant tout une aventure internationale.
Début mars 2026, notre équipe compte 21 personnes représentant 9 nationalités différentes. Cette diversité est l’une de nos plus grandes forces, et l’anglais est la langue qui nous permet de collaborer, de débattre d’idées et de construire ensemble.
Nous sommes très attachés à notre ancrage dans les Alpes françaises, mais chez Mantle8 notre langue commune est l’anglais — que ce soit pour les réunions, les discussions techniques, les e-mails et, oui, même nos blagues.
Donc si vous envisagez de nous rejoindre, l’anglais n’est pas seulement utile : il est essentiel pour faire partie de l’aventure.
On 4/20/2026