The reactions of (1) CH4 +MgO→MgOH¥ +CH3¥ and (2) CH4 + MgO→Mg+CH3OH have beenstudied on the singlet spin state potential energy surface at the MP2/6-311+G(2d,2p) level. These two reactionchannels, both involving intermediates and transition states, have been rationalized by the structures of thespecies involved, natural bond orbital (NBO), and vibrational frequency analysis. We have considered twoinitial interacting models between CH4 and MgO: a collinear C-H approach to the O end of the MgOforming the MgOCH4 complex with C3V symmetry and three hydrogen atoms of the methane point to the Mgend of the MgO forming the OMgCH4 complex with C1 symmetry. The calculations predict that reactions 1and 2 are exothermic by 39.8 and 86.5 kJ mol-1, respectively. Also, the former reaction proceeds more easilythan the latter, and the complex HOMgCH3 is energetically preferred in the reaction of MgO + CH4.