Addressing the significant CO₂ emissions from calcium aluminate cement (CAC) production is a critical challenge for the building and infrastructure sectors, with fossil fuels accounting for a large portion of the greenhouse gas (GHG) footprint. To tackle this, we initiated the PRECIZE (PRocédé ÉCologique et Innovant de liants de spécialité Zéro Émission) project, a strategic collaboration with Air Liquide, “Laboratoire de Génie Chimique” (LGC) in Toulouse, and “Conditions extrêmes et Matériaux: Haute Température et Irradiation” (CEMHTI) in Orléans. Funded by the French state as part of the France 2030 program and operated by ADEME, this initiative is a strategic component of our commitment to science-based targets. One of the key objectives of this project is to demonstrate a scalable pathway to decarbonize CAC production by replacing fossil fuels with a carbon-free alternative like hydrogen. Our study presents the methodology and findings of a successful 12-day pilot trial conducted at our Dunkerque site, detailing the progressive transition from a mixture of 100% natural gas to a 100% hydrogen. The results of this extensive pilot trial will be presented in this paper. We will provide a comprehensive analysis of the impact on CAC quality and performance, as well as on kiln behavior and stability.