Abstract. Effect of radiation on free convection on heated horizontal circular has been investigated. The cylinder is fixed and immersed in a stationary fluid, in which the temperature is uniformly heated about the temperature of the surrounding fluid. The governing equation are transformed into dimensionless non-linear of partial differential equations and solved numerically by employing a finite difference method. An implicit finite difference scheme of Crank Nicolson method is used to analyze the results. This study determine the effects of radiation parameter, heat generation parameter, and the Prandtl number, , on the temperature and velocity profiles. The results of the local heat transfer and skin-friction coefficient in the presence of radiation for some selected values of Prandtl number and heat generation parameter have shown graphically.