tThe Ni2P/-Al2O3and Ni/Al2O3catalysts were prepared, characterized, and evaluated for dehydrogena-tion of cyclohexane. The Ni2P/Al2O3catalyst exhibited superior activity, selectivity and stability to those ofthe Ni/Al2O3catalyst. Characterization results indicate that the small positive charge of Ni and the ensem-ble effect of P in Ni2P can inhibit sintering of Ni2P and promote reactivity of Ni2P in dehydrogenation ofcyclohexane. Moreover, the in situ Fourier transform infrared spectra further reveal that the P-coveredNi(2) sites (Ni3P P sites) of Ni2P(0 0 0 1) are responsible for dehydrogenation of cyclohexane. Meanwhile,the hydrogen temperature-programmed desorption experiments indicate that the Ni2P/Al2O3catalystcontains a large amount of the Ni(2) sites.