The decomposition mechanisms of methylamine on Pd(1 1 1) has been systematically investigated with the DFT-GGA method using the repeated slab model, and the decomposition network has been mapped out. The adsorption energies under the most stable configuration of the possible species and the energy barriers of the possible elementary reactions involved are obtained in this work. Desorption is preferable for adsorbed methylamine and hydrogen, while for the other species decomposition is preferred. Through systematic calculations for the reaction mechanism of methylamine decomposition on Pd(1 1 1), we found the most likely decomposition path is H3CNH2 > H2CNH2 > HCNH > HNC + HCN > CN + H-2. The decomposition products are in general agreement with the previous experimental observations. (C) 2013 Elsevier B.V. All rights reserved.