The hydrodealkylation reaction of ethylbenzene over nickel or nickel-tungsten supported catalysts was studied in a flow reactor system. Toluene was a major product at 350 ℃ over nickel supported catalyst and the conversion of ethylbenzene and the selectivity of benzene increased at higher temperature. Above 450 ℃, methane hydrocracked from aromatic ring was only produced. The product distributions of m-xylene with reaction temperature were similar to those of ethylbenzene. The hydrocracking of aromatic ring of ethylbenzene was restrained at 550 ℃ over nickel-tungsten supported catalyst. When tungsten was added to nickel supported catalyst, decrease of catalytic activity and increase of selectivity for benzene were observed. The electron energies of supported nickel and tungsten, observed in Auger electron spectra were varied with the composition of supported material. The reversible adsorption heat of benzene determined at the range of 100-190 ℃ decreased with increasing the content of tungsten. The increase in the selectivity for benzene due to the co-impregnation of tungsten might be explained in terms of the reduction of catalytic activity for hydrocracking reaction with decrease in the adsorption strength of benzene on the catalysts by the interaction between supported nickel and tungsten.