The scaling of turbulence statistics for wall-bounded thermal turbulent flow with different total heat flux gradients was investigated using direct numerical simulation (DNS) of an incompressible turbulent channel flow with passive scalar transport at the friction Reynolds number of 300 and the Prandtl number of 0.72. DNSs for four cases were performed, where the non-dimensional total heat flux gradients were -1, -0.5, 0 and +0.5. It was revealed that temperature variance and turbulent heat flux were well scaled by the local friction temperature. In addition, using the linear stress-heat flux model, it was shown that the appearance of the logarithmic temperature profile was attributed to the distribution of the turbulent Prandtl number. (c) 2006 Elsevier Ltd. All rights reserved.