The experimental temperature transition and freezing times of sucrose solution droplets were acquired to validate a numerical model. In addition, experiments were undertaken to determine the effect of sucrose on the external mass transfer from droplets. Results showed that the addition of a solute significantly affected the mass transfer from freezing droplets. For the accurate modelling of any spray crystallisation process of aqueous solutions, the solute effects must be quantified. Comparisons of numerical model predictions against experimental data revealed that discrepancies increased with decreasing air temperature. This is likely to be due to solidification becoming increasedly non-equilibrium at high freezing rates. Therefore, to increase the accuracy range of the numerical modelling approach, non-equilibrium effects will need to be incorporated in future models. (C) 2004 Elsevier Ltd. All rights reserved.