Disclosed herein is an integrated process for production of electricity, hydrogen, and water using a high-temperature gas-cooled reactor as a single source, including: the high-temperature gas-cooled reactor, a power conversion unit connected directly or indirectly with the high-temperature gas-cooled reactor to receive heat produced by a reactor core of the high-temperature gas-cooled reactor and drive a gas turbine by the heat, thereby producing electricity through an electric generator, a hydrogen production unit that produces hydrogen by receiving the heat produced by the high-temperature gas-cooled reactor and/or the electricity produced by the electric generator, an electrical desalination unit that produces water by using the electricity produced by the electric generator, and a thermal desalination unit that produces water by distilling fresh water from salt water with waste heat recovered from a precooler and an intercooler of the power conversion unit.