Hydrogen production with a fast breeder reactor (FBR) may be attractive as a long-term energy source with nuclear fuel breeding. The thermochemical and electrolytic hybrid process is one of the hydrogen production methods using a sulfuric acid cycle with the maximum temperature at 500°C, which can be supplied by a sodium-cooled FBR. In this study, a hydrogen production plant with the thermochemical and electrolytic hybrid process has been designed, and the hydrogen production efficiency has been evaluated. The structural materials of the components in the system are steels such as high-Si cast iron, which has good toughness against sulfuric acid. High hydrogen production efficiency of 44% (high heating value) is achieved assuming development of high-efficiency electrolysis.