A study has been carried out to analyze the thermophoretic particle deposition and heat generation/absorption effects on unsteady, free convective, viscous fluid flow over a moving flat plate. The thermal conductivity of the fluid is assumed to vary as a linear function of temperature. The governing partial differential equations are solved numerically by using an implicit finite difference method of Crank Nicolson type. Numerical results for the velocity, temperature and concentration profiles as well as for the skin-friction coefficient, Nusselt number and Sherwood number distributions are obtained and presented graphically for various parametric conditions to show interesting aspects of the solution. Results indicate that the heat source/sink plays a vital role in predicting the heat transfer characteristics of moving fluids and the thermophoretic particle deposition has notable influence on the mass transfer characteristics. © 2017 Society of Thermal Engineers of Serbia.