The effects of Reynolds and Prandtl numbers on the heat transfer characteristics of an isolated square cylinder have been investigated for the range of conditions 1 = Re = 45 and 0.7 = Pr = 4,000 (the maximum value of Peclet number being 4,000) in crossflow. Heat transfer correlations are obtained for the constant cylinder temperature and constant heat flux boundary conditions on a solid square cylinder in the steady flow regime. In addition, the variation of local Nusselt number on each face of the obstacle and representative isotherm plots are presented to elucidate the role of Prandtl number on heat transfer in the steady flow regime.