Recently, cerium oxides have been extensively used as heterogeneous catalysts for green organic reactions. This review describes recent progress in such reactions, with a focus on our studies on pure CeO2-catalyzed reactions of nitrites and amides with nucleophiles (H2O, alcohols, and amines). Hydration of nitrites to amides in water, one-pot ester synthesis from nitrites and alcohols, one-pot synthesis of N-alkylamides from nitrites with amines, and synthesis of N-alkylamides from amides and amines (transamidation) are selectively catalyzed by CeO2 under aqueous or solvent-free conditions. Mechanistic studies suggest that a cooperation of Lewis acid site (Ce4+ cation) and acid-base (Ce-O) pair site plays essential roles in the catalytic reactions.