Manganese(Ⅲ) meso-tetraphenylporphyrin acetate [Mn(TPP)OAc] served as an effective catalyst for the oxidative decarboxylation of carboxylic acids with (diacetoxyiodo)benzene [PhI(OAc)2] in CH2Cl2-H2O(95:5,volume ratio). The aryl substituted acetic acids are more reactive than the less electron rich linear carboxylic acids in the presence of catalyst Mn(TPP)OAc. In the former case,the formation of carbonyl products was complete within just a few minutes with >97% selectivities,and no further oxidation of the produced aldehydes was achieved under these catalytic conditions. This method provides a benign procedure owing to the utilization of low toxic(diacetoxyiodo) benzene,biologically relevant manganese porphyrins,and carboxylic acids. Manganese (Ⅲ) meso-tetraphenylporphyrin acetate [Mn (TPP) OAc] served as an effective catalyst for the oxidative decarboxylation of carboxylic acids with diacetoxyiodo benzene [PhI (OAc) 2] The aryl substituted acetic acids are more reactive than the less electron rich linear carboxylic acids in the presence of catalyst Mn (TPP) OAc. In the former case, the formation of carbonyl products was complete within just a few minutes with> 97% This method provides a benign procedure due to the utilization of low toxic (diacetoxyiodo) benzene, biologically relevant manganese porphyrins, and carboxylic acids.