WC nanoparticles were synthesized using a variation of pulsed laser deposition (PLD) process. In this modified PLD the ablated plume is carried away by a circulating carrier gas from the evaporation region. It is then allowed to condense heterogeneously and the condensed particles are collected on a filter. Using this technique we synthesized two different types of particles, as-prepared WC and pure W nanoparticles. Pure W nanoparticles were subsequently carburized to form WC. These nanoparticles were used to study the feasibility for the use in NO, reduction. The structural and chemical properties of these samples were analyzed using x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). Catalytic activity was measured using a tube reactor. A combination of 1 % NO and 99% He gas was used. Both the pure WC and carburized WC samples were found to be catalytically active with an activation temperature of about 400 degrees C. The stability of the catalysts was studied by performing de-NOx experiments for an extended period of time. Both XRD and XPS analyses of the samples after de-NOx confirm the formation of oxide. CO addition helped to reduce the extent of oxide formation. (c) 2007 American Vacuum Society.