This paper presents the effect of thermal radiation on the boundary layer over a flat plate. The convective boundary condition is applied at the surface of the flat plate. The solution to the coupled non-linear transport equations is obtained using the Runge-Kutta-Fehlberg fourth-fifth order (RKF45) method. The impact of thermal radiation on mercury, air, sulphur oxide and water whose Prandtl numbers ( Pr ) are 0.044, 0.72, 2, and 7 respectively are depicted using line graphs and tables. The impact of Prandtl number ( Pr ), local convective heat transfer (a) and temperature difference ( C T ) on temperature distribution are also presented. The results indicated that the boundary layer thickness decreases with Pr augment but increases with increasing values R . Furthermore, R augment is inversely proportional to the temperature gradient near the plate while an opposite trend is observed away from the plate. The results also indicated that R augment reduces heat transfer but an opposite trend is observed with Pr augment. Pr augment has a decreasing effect on boundary layer thickness and a augment has an increasing effect on temperature.