To find a suitable metal component in an oxygen carrier particle for a chemical-looping hydrogen generation system (CLH), oxygen transfer capacities of metal components were investigated, and Ni was selected as the best metal component. The optimum operating conditions to have maximum hydrogen generation rate have been determined based on the chemical-equilibrium composition analysis in a water splitting reactor. Moreover, suitable compositions of syngas from a gasifier of heavy residue oil to provide high energy efficiency have been determined based on the heat of reaction. With the selected operating conditions, the best configuration of two interconnected fluidized beds system for the chemical-looping hydrogen generator has been devised.