In order to provide a practical strategy for solving mass transfer fields across air-water interfaces, an extended version of the analytical wall-function (AWF) is presented. (This wall-function is designed for Reynolds averaged Navier Stokes simulations.) By considering exact near-surface limiting profiles of turbulence quantities such as the eddy viscosity and the turbulent scalar flux, the prescribed turbulent diffusivity profile, which is a core assumption of the AWF, is modelled to have the correct limiting behaviour. The resultant AWF performs well to predict surface mass transfer rates and turbulent concentration fields across undeformable air-water interfaces at Schmidt numbers of 1 <= Sc <= 1000. (C) 2010 Elsevier Ltd. All rights reserved.