A new procedure for the prediction of wall temperatures in vertical tubes has been established in the framework of the development of the High Performance Light Water Reactor (HPLWR). The prediction of the wall temperature is accomplished by a look-up table for heat transfer in supercritical water. The look-up table lists the wall temperatures as a function of mass flux, heat flux, pressure, tube diameter, and bulk enthalpy. Based on an extended literature survey, experimental data for different conditions of upward flows in vertical smooth tubes are selected. To exclude data which exhibited local, buoyancy driven effects, a criterion of Jackson for deterioration of heat transfer is used to remove these data from further processing. An interpolation method is applied to assemble the tabulated grid points, based on published correlations for heat transfer in supercritical water. The look-up table covers a mass flux range of 700e3500 kg/m 2 s, a heat flux range of 300e1600 kW/m 2 , a pressure range of 22.5e25 MPa, a diameter range of 8e20 mm and a bulk enthalpy range of 1200e2700 kJ/kg. Extreme combinations which required extrapolation of the data are excluded. The accuracy of the table in the vicinity of the pseudo-critical point is significantly higher than published correlations.