The new distributed parameter model is formulated for the purpose of the investigation of spray drying of multi-component solutions. The main feature of this model is the division of a droplet/wet particle into shells and formulating the mass and heat balances for each shell. In opposition to most similar numerical models, this one takes into account the crust formation during the second stage of drying. By means of this model, we investigate the conditions in which the segregation of the components in particle form takes place. We take into account the initial concentrations of the components in solution, its solubility and diffusion coefficients as model parameters for consideration of the different particle structures. (C) 2012 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.