Logarithmic wall laws of mean axial velocity and temperature are obtained for the heated inner wall of a vertical concentric annular channel from measurements in turbulent,liquid flow. The temperature wall law has limited generality because Prandtl number only in the range 7-8 is considered. When the influence of the buoyancy force as indicated by the parameter Gr(q)/Pr Re-4 becomes large, the velocity and temperature data do not follow the respective wall laws. (C) 1997 Elsevier Science Ltd.