The two novel green oxidation processes of p/o-cresols to p/o-hydroxybenzaldehydes catalyzed by metalloporphyrins in the presence of molecular oxygen were developed in this work. Among the metalloporphyrins with different central ions and substituents studied, T(p-NO2)PPCoCl and T(p-OCH3)PPFeCl presented the highest activities for p-cresol and o-cresol oxidation reactions respectively. The molar ratio of sodium hydroxide to cresols and different reaction parameters including reaction temperature, reaction time and reaction pressure have been investigated, and 69.8%/50.4% conversions of p/o-cresol and 86.6%/26.6% selectivities for p/o-hydroxybenzaldehydes were reached under optimized conditions.