A computational study is carried out on a vertical hollow cylinder with a finite wall thickness for the combined effect of natural convection heat transfer with surface radiation. The Navier-Stokes equation, energy equation, and radiation equation are solved using ANSYS-Fluent 18 using the finite volume method to determine flow and heat transfer characteristics around the vertical hollow cylinder. The validation of the current numerical scheme is also presented with available literature. The aspect ratio (length to diameter ratio) of the cylinder is kept constant, i.e., 2 in the analysis. Various pertinent input parameters, such as Rayleigh number, surface temperature, and different cylinder material conductivity, are varied. The effect of various radiation models such as the Rosseland model, P1 model, DTRM, DO model, and S2S model is presented here. Results contain Nusselt number variation with the different parameters for both convection and radiation. The overall heat transfer increases with an increase in surface temperature as well as surface emissivity. It also observed that the inclusion of radiation with convection heat transfer is essential in net heat transfer rate calculation.