Drying of suspensions and paste-like materials on inert particles in the Mechanically Spouted Bed (MSB) drier was studied by the author. Radioactive isotopic tracer technique was used for measuring the Cycle Time Distribution (CTD) of the inert particles. Effect of gas velocity and peripheral speed of the houseless screw was studied on variance (sigma2) of CTD. It was found that solid particle circulation could be characterized by plug flow. The three partial processes of drying on inert particles, namely: coating of the particles, drying of coating and abrasion of dried layer, could be separated in space in the MSB drier. In order to provide steady state conditions of drying it is important to predict the time required by the partial processes. Heat and mass transfer coefficients were calculated on the drying model.