Calyos turns thermal management into a strategic asset for Europe.

Walloon startup Calyos is gaining momentum as it positions its passive cooling technology at the heart of Europe’s critical infrastructure, spanning digital, energy and defence sectors.

The company develops fully passive, two-phase cooling systems capable of dissipating heat without pumps or moving parts, delivering significant gains in energy efficiency, reliability and sustainability.

As Europe accelerates its push for technological sovereignty, cooling is becoming a strategic challenge. Data centres and compute platforms—essential to both the digital economy and defence operations—require resilient, efficient and resource-independent solutions.

Calyos’ technology directly addresses these needs. Originating from space engineering, its systems rely on phase-change processes where a fluid evaporates and condenses in a closed loop, ensuring continuous cooling without additional energy input.

This innovation has been recognised by NATO through its DIANA programme, which supports high-potential dual-use technologies aimed at strengthening energy efficiency, resilience and operational autonomy.

Beyond defence, Calyos is already deploying its solutions across key industries including e-mobility, batteries and high-performance computing, with real-world use cases emerging in motorsport, automotive and micro-mobility.

Rooted in Wallonia and supported by innovation hubs such as A6K, the startup is scaling through strategic partnerships across Europe. Its ambition: to become a leading player in advanced thermal management while contributing to Europe’s industrial and technological independence.

A clear signal that deeptech startups from Wallonia are playing an increasingly strategic role on the European stage.