HYTHEC - HYdrogen THErmochemical Cycles – is an EC funded project that is investigating the potential for massive scale hydrogen production by the Sulphur-iodine (SI) thermo-chemical cycle as well as the Hybrid-Sulfur (HyS) cycle. Both have in common the H2SO4 decomposition reaction. The overall project approach is multi-faceted. It includes modelling of the thermochemical steps, flow-sheeting, and experimental measurements of the decomposition of H2SO4 in a solar furnace at high temperatures. It also involves, measurements of the partial pressures above a mixture of HI, H2O and I2, modelling and experimental exploratory research into alternative, low energy separation techniques relevant to the SI process such as membranes, and the industrial scale-up, safety and cost analysis of H2 production by coupling the SI cycle to a nuclear reactor and the Hybrid-Sulfur cycle to a solar and/or a nuclear source. A first SI and HyS cycle analysis round was completed. This involved SI flow-sheet development and detailed considerations of industrial scale-up including a first cut economic evaluation. Experimental results were then obtained on the H2 production step (liquid vapour equilibria and membranes) and on H2SO4 decomposition. A second stage of analysis has now begun involving more work on industrial scale-up and cost assessments that take into account modelling from the first round. Collaborations have been entered into with other European projects (RAPHAEL, HYSAFE, EXTREMAT). The HYTHEC project has been recognized and endorsed by the Steering Committee of the International Partnership for the Hydrogen Economy (IPHE).