High Temperature Electrolysis (HTE) of water steam is currently considered as a high potential process for massive hydrogen production. Comparing this process with the widely known Water Alkaline Electrolysis, a decrease in electric energy consumption was observed. However, under the current international context that demands lower greenhouse gas emissions in industrial processes, the choice of the energy source that would supply electricity and heat to the HTE process is the main concern for its competitiveness and sustainability. In this work, we propose the HTE process coupled to a Sodium Nuclear Reactor. For the HTE, the modelling of the electric characteristics was performed with an electrochemical model based on the mass and energy balance, the Butler-Volmer equation, Fick’s model and Ohm’s law. Concerning the Sodium Nuclear Reactor, a partial drawing off of the water steam from the reactor’s turbine was proposed. Based on a simplified flowsheet of the complete process and using genetic algorithms, the techno-economic study of the above mentioned novel coupling was performed for different cost scenarios. The main elements considered in the techno-economic study are the cell investment costs, energy consumption and lifespan, the energy costs and the heat exchangers investment costs. Varying the electricity and investment costs, the results show that a hydrogen production cost between 2 and 4 euros per kilogram could be reached.