Abstract: A novel fixed-bed solar reactor system via ceria redox is presented for thermochemical water splitting.Transient lumped parameter method is used for modelling the whole system including reduction,heat recuperation and oxidation processes.Based on the present technology conditions,the heat recovery effectiveness of solid phase and the overall thermal efficiency are predicted up to 81% and 27% respectively,with optimized parameters of cavity numbers,nitrogen gas flow rate,and reduction temperature.Then,sensitivity analyses regarding gas phase heat recovery effectiveness and optical concentration ratio are also conducted.