HyCoFlex is aiming at the development of a retrofitable decarbonisation package for cogeneration of power and industrial heat with 100%-fired gas turbines. The solution will be integrated and fully demonstrated at an industrial site in Saillat-sur-Vienne in France. HyCoFlex will leverage on and further advance the infrastructure of a power-to-hydrogen-to-power industrial scale plant which was developed and demonstrated within the HYFLEXPOWER project. The project will develop operational flexibility capabilities and protocols to satisfy the typical operating profiles experienced by industrial cogeneration plants. By doing so, HyCoFlex will elaborate credible pathways for upscaling and replicating the retrofit package, ultimately accelerating the achievement of industrial and energy sector decarbonisation. In order to meet the global objective, within the HyCoFlex project, the HYFLEXPOWER plant concept and infrastructure will be implemented for 100% H2-fuelled cogeneration. In the framework of the project a Siemens Energy SGT-400 gas turbine will be upgraded with an advanced dry low-emission (DLE) H2 combustion system to operate with different natural gas / H2 fuel mixtures. The retrofitted demonstrator plant will be validated for flexible operation under various natural gas/hydrogen mixtures and loads, while aiming at overcoming state-of-the-art efficiencies with decreased NOx emissions. Finally, HyCoFlex will explore pathways for upscaling and commercialization of decarbonised power generation from gas turbines within a circular-economy framework.