The cerium-catalyzed syntheses of hydroxybenzaldehydes from cresols by oxygen oxidation have been developed. When cerium catalyst four-coordinated by hydroxo ligand was employed, the oxidation process required much less catalyst (0.5%), a shorter reaction time (5 --> 2 h) and a lower temperature (120 --> 40-degrees-C). The rate of two first-order reactions increased by a factor of c. 10(6).