The development of a two-dimensional mathematical model to calculate flow characteristics in channels of compound cross-section is described. The model utilizes a previously developed depth-averaged form of thek-ε turbulence model. The model is tested against velocity and bed shear stress data taken from the literature and obtained in laboratory flumes modelling a main channel/flood plain geometry. Comparisons between these data and model predictions show generally good agreement. One necessary input to the model is the dimensionless transverse eddy diffusivity,e*ast;, which has a significant influence on the predicted distributions. A value of0.15, adopted from the literature for rectangular laboratory flumes, is shown to be appropriate for laboratory compound channels. However, application of the model to natural compound channels requires further investigation of this parameter.