CeO2 samples were prepared by Ce(NO3)3·6H2O decomposition under synthetic air or 5%H2/N2 at 500°C. The samples were characterized by XRD, N2 adsorption at −196°C, Temperature Programmed Reduction with H2 (H2–TPR) and DRIFTS. The catalytic activity for CO oxidation was also tested. The main conclusion is that H2 accelerates the decomposition of cerium nitrate to CeO2 with regard to air decomposition, allowing preparation of ceria with enhanced catalytic behavior. The gas atmosphere used in the decomposition of the nitrates has no effect in the crystal size and surface area of the ceria samples obtained.