Ru/C catalysts were prepared from commercial activated carbon submitted to different treatments. The catalysts were prepared by incipient wetness impregnation, through an aqueous solution of the precursor RuCl3 center dot xH(2)O. After impregnation, some catalysts were submitted to direct reduction treatment under H-2 flow at the temperature of 150 degrees C, in order to evaluate the effects of activation. The supports were characterized by N-2 adsorption, Boehm and potentiometric titration. The X-ray photoelectron spectroscopy was used to study the supports and catalysts surfaces, while scanning electron microscopy allowed us to determine the chemical composition and observe the catalysts morphology. Ru/C catalysts performance was evaluated within the hydrogenation reaction of benzene in liquid phase, using a Parr reactor. The reaction was conducted under total pressure of 5.0 MPa of H-2, at a temperature of 100 degrees C with water in the reaction medium. The obtained results indicate that the Ru/C system catalytic performance is influenced for determined functional groups present on the activated carbon surface. The carbonyl groups decrease the activity and selectivity of the reactions, while an increase of the carboxylic groups leads to more active catalysts and the highest yield of cyclohexene. (C) 2011 Elsevier B.V. All rights