Surface divergence models for prediction of scalar exchange at fluid-fluid interfaces are investigated. The models, based on the Hunt-Graham blocking theory, are shown to predict experimental data at unsheared interfaces, and new results of direct numerical simulation for deformable, nonbreaking sheared interfaces. The parameterization is in terms of the turbulent Reynolds number defined by the integral velocity and length scales in the bulk flow, which makes it useful for practical purposes. (C) 2004 Elsevier Ltd. All rights reserved.