Heat-transfer coefficients for supercritical water are presented for flow in an electrically heated AISI Type 304 stainless-steel tube having an inside diameter of 0.300 in. Bulk fluid temperatures were varied from 220 to 1000 F at 4500 psi, and over a more limited temperature range at 3500 psi. Mass flows tested include 1.6 to 2.5 × 106 lb/hr-sq ft, and a flux range of 280,000 to 580,000 Btu/hr-sq ft was covered. Values of film conductance in the vapor region were found to be substantially higher than those predicted by extrapolation of data found in the literature, or by recent formulas based on a theoretical approach. These findings are of special interest to the boiler industry which is presently designing units for use at supercritical conditions.