Two fundamental properties of the particles are their velocity and consequent displacement versus time history during the granulation process. Knowledge of the particle velocity might supply much information about the sub-processes. In this paper, an analytical model of a solid particle motion in an internal re-circulatory fluidised bed unit is developed and validated against experimentally obtained data. The model predictions show good correspondence with the experimental results for the spherical particles. For the case of non-spherical granules, the agreement between the model and the experiments is not equally convincing but still adequate.