Radiation and chemical reaction effects on heat and mass transfer in non-Da..Radiation and chemical reaction effects on heat and mass transfer in non-Darcy non-Newtonian fluid over a vertical surface is considered. In this article we have maintained the constant temperature. A mathematical model is developed taking into the account the new elements introduced. Numerical solutions for the governing nonlinear momemtum, energy and concentration are obtained.The governing boundary layer equations and boundary conditions are simplified by using similarity transformations. The governing equations are solved numerically by means of Fourth-order Runge-Kutta method coupled with double-shooting technique. The influence of viscosity index n , thermal and solute dispersion, velocity, temperature, concentration, Heat and mass transfer rates are discussed.