The adsorption and reaction of 1-butene on Mo2N/gamma -Al2O3 catalyst have been studied by in situ FT-IR spectroscopy at low temperatures, 145 K to room temperature (RT). The adsorbed 1-butene can be converted to cis- and trans-2-butenes below 201 K on Mo2N/gamma -Al2O3 catalyst. The result of coadsorption of 1-butene with CO indicates that 1-butene is mainly adsorbed on the surface Mo sites of the nitrided catalyst. No isomerization of adsorbed 1-butene and 2-butenes on reduced passivated Mo2N/gamma -Al2O3 sample below RT is observed. It is suggested that the double-bond migration (DBM) of 1-butene is mainly proceeded via an alkyl species on the surface cus Mo sites of Mo2N/gamma -Al2O3 catalyst. This resembles the behaviors of Group VIII metals in the isomerization of butenes. The incorporated nitrogen atoms are proposed to devote to both the valence state of surface Mo sites and the interaction between 1-butene and the nitrided catalyst. A possible path from 1-butene conversion to 2-butenes on Mo2N/gamma -Al2O3 catalyst is proposed.