For bimetallic catalysts, the composition of each metal component has a crucial effect on their catalytic performance. In this work, the Ni/Ni(OH)(2)/C sample is synthesized at room temperature (RT) by a simple hydrazine hydrate reduction method using carbon black as support, and then Ru-Ni/Ni(OH)2/C is prepared via galvanic replacement reaction based on Ni/Ni(OH)(2)/C. The Ru-Ni/C catalyst can be obtained when Ru-Ni/Ni(OH)(2)/C is annealed in N-2 at 380 degrees C. The different compositions of Ru-Ni bimetallic catalysts are successfully controlled by adjusting the addition amount of aqueous RuCl3 solution during the galvanic replacement process. The RuxNiy/C catalysts (the subscripts represent atomic ratios) are evaluated by the reaction of the hydrogenation of benzene to cyclohexane and the experimental results reveal a strong correlation between the catalytic activity for benzene hydrogenation and Ru/Ni atomic ratios. The Ru0.56Ni0.44/C catalyst exhibits the highest catalytic performance among the RuxNiy/C catalysts in this work. The characterizations of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM) and EDS-elemental mapping for the Ru0.56Ni0.44/C catalyst demonstrate that the nanostructure of Ru-onNi/Ni0 nanoparticles can improve its catalytic properties. (C) 2015 Elsevier B.V. All rights reserved.