A series of C/SiC composites was successfully synthesized via the carbothermal reduction of carbonaceous silicon xerogel, which was prepared from the sol gel method by using tetraethoxysilane TEOS and saccharose as the raw materials. The obtained samples were characterized by X-ray powder diffraction XRD and N-2 physical adsorption. The specific surface areas of the as prepared C/SiC composites varied from 329 to 849 m(2)/g. The average pore diameters and the total pore volumes were in the range of 4.5-7.6 nm and 0.53-1.12 cm(3)/g, respectively. The as prepared C/SiC composites were proved to be effective supports for Ru catalysts for ammonia synthesis At 435 degrees C, 10.0 MPa and a N-2/H-2 (1/3) flow rate of 10000 h(-1), the optimum activity of 15.9% ammonia in the effluent was reached when C/SiC-5 (C/TEOS) molar ratio = 5) was used as the catalyst support. (C) Elsevier B.V. All rights reserved.