The exposure of preadsorbed oxygen to monomethylamine or the coadsorption of a 2:1 monomethylamine (CH3NH2)/dioxygen mixture at a Cu(211) surface at room temperature results in the formation of a surface species characterised by C(1s) and N(1s) binding energies of 285.2 and 398.2 eV, respectively, with a calculated carbon to nitrogen ratio of 2:1. This species, which we assign to a chemisorbed dimethylamine ((CH3)(2)NHx(a)), is the only adsorbed product of the reaction and its formation must involve the breaking of a carbon-nitrogen bond and the intermolecular transfer of a methyl group.