Based on numerical Solutions of the balance equations accurate empirical correlations for filmwise condensation in forced convection flow over a horizontal flat plate are presented. The correlations are designed to be also correct for the limiting case of zero and infinite condensation rate. They are applied to determine the interface temperature between liquid and vapour phase and hence the condensation rate and heat flux. The results are in excellent agreement with those from numerical Solutions of the balance equations. It turns out that the usually adopted film theory for the vapour-phase mass transfer overestimates the size of a heat exchanger. (c) 2005 Elsevier Ltd. All rights reserved.