This paper presents results for the deposition rate of small particles on the walls of a turbulent channel flow. The results were obtained by direct numerical simulation of a horizontal turbulent channel flow. A temperature profile typical of ceramic oxide aerosol reactors was imposed across the channel. Thermophoresis played an important role in the deposition of particles for the range of conditions that were studied. An interaction. between turbophoresis and thermophoresis was found to play an important role in the deposition process.