WC powder was synthesized by a nitridation-carburization method with WO(3) prepared by the citrate sol-gel route as the starting material, and the reaction mechanism was investigated. It was found that WO(3) was converted to nanosized W(2)N after the nitridation process in NH(3). Then, the W(2)N was transformed to W metal, W(2)C, and WC in sequence when it was carburized in CH(4)-H(2) gas mixture. The WC powder obtained possessed a high specific surface area of 24.6 m(2)/g, and showed a particle size of 20-30 nm, which was much finer than the WC powder prepared by direct carburization of WO(3) in CH(4)-H(2) gas mixture. The reason was also discussed.