A comprehensive model is presented for predicting the rate of steel corrosion in concrete structures and the consequent formation and propagation of cracks around the steel reinforcement. The corrosion model considers both the initiation and the propagation stages of corrosion. Processes commencing in the initiation stage, such as the transport of chloride ions and oxygen within the concrete and variation in temperature and moisture, are assumed to continue in the propagation stage while active corrosion is occurring contemporaneously. This allows the model to include the effects of changes in exposure conditions on the corrosion rate and the effects of the corrosion reactions on the transport properties of concrete. The corrosion rates are calculated by applying the finite-element solution of the Laplace equation for electrochemical potential, with appropriate boundary conditions. Because these boundary conditions are nonlinear, a nonlinear solution algorithm is used. The results of the analysis are compared with available test data, and the comparison is found to be satisfactory. Key words: reinforced concrete, steel corrosion, finite-element modelling, durability.