Several solar thermochemical reactors have been developed to split water by a two-step water-splitting cycle with redox metal oxide utilizing concentrated solar thermal energy in sunbelt region. A windowed solar reactor using a reactive foam device made of redox metal oxide is one of the promising reactor. In this study, small foam devices of metal-doped ceria (CeO2) were fabricated and tested on their reaction performances in a lab-scale windowed reactor using a 3kWth sun simulator. The foams of Fe or Ni-doped ceria produced more than twice as much as hydrogen in comparison to benchmark CeO2 foam.