The adsorption and decomposition of N 2 O on GaN (0001) surface has been explored employing density functional theory. Our calculations indicate the parallel adsorbed N 2 O prefers to be dissociated on the surface, and the dissociated O atom is combined at fcc site, the N–N piece is adsorbed on top site of the surface or desorbed from the surface. From the potential curve of the reaction process of N 2 O dissociation on the surface, an energy barrier of 0.11eV is derived, which is smaller than that of many widely studied adsorbents for N 2 O decomposition.