Temperature-programmed reduction in a H₂/Ar mixture of Rh-loaded CeO₂-ZrO₂ solid solutions with a ZrO₂ content varying between 10 and 90% mol and of monoclinic, tetragonal, and cubic structures is reported. It is shown that incorporation of ZrO₂ into a solid solution with CeO₂ strongly promotes bulk reduction of the Rh-loaded solid solutions in comparison to a Rh/CeO₂ sample. The promotion of the bulk reduction results in high oxygen storage capacity (OSC) as measured by oxygen uptake. A structural dependence of both reduction and oxidation processes is observed which is attributed to a higher oxygen mobility in the cubic structure compared to the tetragonal and monoclinic ones.