Comprehensive temperature-programmed reduction, X-ray diffraction and diffuse reflectance spectroscopy studies were conducted on a stable nickel (10.5%) catalyst obtained through conventional impregnation of a sol-gel made support of g-Al2O3, to elucidate the interactions between nickel oxide and support. The results pointed to the presence of a NiAl2O4 spinel layer on the surface produced by the strong interaction between NiO and the support. These interactions might be responsible for its high activity, stability and resistance to coking