We report the catalytic activity of Au/TiO2 and Pt/TiO2 nanocatalysts under CO oxidation fabricated by arc plasma deposition (APD), which is a facile dry process involving no organic materials. Using APD, the catalyst nanoparticles were well dispersed on the TiO2 powder with an average particle size of 2-4nm, well below that of nanoparticles prepared by the sol-gel method (10nm). We found that the average particle size of the dispersed gold nanoparticles can be controlled by changing the plasma discharge voltage of APD. Accordingly, the amount of gold loaded on the TiO2 powder increased as the discharge voltage increased, but the specific surface area of the Au/TiO2 samples decreased. As for catalytic reactivity, Au/TiO2 showed a higher catalytic activity than Pt/TiO2 in CO oxidation. The catalytic activity of the Au/TiO2 samples showed size dependence where higher catalytic activity occurred on smaller gold nanoparticles. This study suggests that APD is a simple way to fabricate catalytically active nanocatalysts. (C) 2013 Elsevier B.V. All rights reserved.