In this paper, boundary layer flow of non-Newtonian Casson fluids past a semi-infinite porous plate in the presence of thermal radiation, viscous dissipation and heat generation is explored. Fluids of this type act as solid elastic and they are very important in food technology, biological science, etc. The flow took place over a semi-infinite vertical porous plate. The presence of viscous dissipation in the flow equations plays a significant role on flows having high viscosity such as polymers and oils. Thermal radiation and heat generation plays a decisive role in the design of many advanced energy conversion system which operates at higher temperature. Hence, the present study is useful in food processing industries and thermal engineering processes. The flows governing equations are numerically solved with spectral relaxation method (SRM). SRM is an iterative procedure that employs the Gauss-siedel type of relaxation approach to linearize and decoupled the system of coupled differential equations. The influence of controlling parameters on velocity, temperature and concentration profiles are plotted in graphs. Furthermore, numerical computations of the local skin friction, local Nusselt number and local sherwood number are presented in tabular form. Results revealed that the presence of the thermophoresis in the concentration equation has great influence on the velocity and concentration profiles because increasing the thermophoresis parameter intensifies the velocity and concentration profiles.