The recycling of cemented carbides is carried out to a significant extent with the zinc decomposition process. The first step exhibits temperatures between 900–1,000 °C, at which zinc can react with the hard metals in three different ways, either liquid, gaseous or as a mixture of both aggregate states. The Co-Zn phases formed in this process lead to an increase in volume and enable the disintegration. As of right now, there is insufficient knowledge available on the reactions taking place and research of the formation of intermetallic layers has been performed mainly with liquid or solid zinc. This work establishes a basis for the disintegration of cemented carbides by zinc vapour to optimize processes and reduce energy consumption. Two newly built test setups allow the decomposition of different materials with vaporous zinc. Varying parameters such as temperature, test duration, zinc amount and pressure are used to investigate the influence of the gaseous disintegration agent. For a better understanding of the phase formation between the binding agent and the solvent, as a strong simplification pure cobalt is used instead of WC-Co cemented carbides. Experiments under vacuum confirm the findings from investigations with liquid zinc. A slight overpressure due to the generated zinc vapour in a sealed crucible shows a positive influence on the decomposition. The Co-Zn phases formed differ from those known in literature. The obtained results indicate a possibility for energy and raw material savings on an industrial scale and thus provide a valuable contribution to resource conservation.