Singlet and triplet potential energy surfaces for the CH3O2 with H reaction have been investigated computationally to propose the reaction mechanisms and possible products. On the singlet PES, addition-dissociation was located. At 3.65 Torr with He as bath gas, the formation of CH2O + H2O channel is dominated at the whole temperature range. Furthermore, the predicted rate constants for k(CH2O+H2O) at 298 K 3.65 Torr of He agree well with the available experimental values. The pathways on the triplet PES will not compete with the pathways on the singlet PES in kinetically. (C) 2017 Elsevier B.V. All rights reserved.