The book provides a comprehensive analysis of radiation and mass transfer effects on an unsteady two-dimensional laminar free convection flow of a viscous, incompressible fluid past a vertical plate with viscous dissipation. The Rosseland approximation is used to describe the radiative heat transfer in the limit of optically thick fluids. Extensive computations have been performed for the effects of the controlling thermo fluid and hydrodynamic parameters on the dimensionless velocities , temperature and concentration, and also on the local and average skin frictions local and average Nusselt numbers and local and average Sherwood numbers. A representative set of numerical results is shown graphically in Figures. Applications of the problem are also discussed.