This work presents an approach to modeling the pneumatic conveying of polydispersed mixtures using the so-called object oriented simulation (OOS) method. Ability to consider a particle size distribution was incorporated into the OOS framework in such a way that it may represent any type of size distribution. Along the model description, several case-studies are accomplished with monodispersed and polydispersed mixtures, which show significant dynamics discrepancies between them, even if the particles mean diameters are the same. This verification is relevant since most of the correlations available to estimate important pneumatic conveying parameters, such as pressure drop and chocking velocity, are based on monodispersed mixtures or use some kind of mean diameter definition. (c) 2006 Elsevier B.V. All rights reserved.