A theoretical study of the effect of thermophoresis on aerosol particle deposition onto a vertical flat plate is proposed. The flow was modeled as a two-dimensional, incompressible and steady-state laminar flow driven by a combination of forced convection and natural convection. The particle deposition mechanisms were coupled using convection, Brownian diffusion and thermophoresis. Similarity analysis with the box method and block-elimination was used to determine the velocity and temperature fields. Particle deposition velocities were solved using the finite difference method or the approach of numerical integration. The effects of thermophoresis and convection were predicted to be particularly important for submicron particles moving toward a cold surface or blowing away from a hot surface at a given temperature gradient. The results also showed that the particle deposition rates were strongly influenced by thermophoresis and buoyancy force, particularly for opposing flow and hot wall surfaces.