The Ni2P/gamma-Al2O3 and Ni/Al2O3 catalysts were prepared, characterized, and evaluated for dehydrogenation of cyclohexane. The Ni2P/Al2O3 catalyst exhibited superior activity, selectivity and stability to those of the Ni/Al2O3 catalyst. Characterization results indicate that the small positive charge of Ni and the ensemble effect of P in Ni2P can inhibit sintering of Ni2P and promote reactivity of Ni2P in dehydrogenation of cyclohexane. Moreover, the in situ Fourier transform infrared spectra further reveal that the P-covered Ni(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/Al2O3 catalyst contains a large amount of the Ni(2) sites. (C) 2013 Published by Elsevier B.V.