When modeling the hydrodynamics of binary particle mixtures differing in size and density in gas-solid bubbling fluidized beds by the multi-fluid Eulerian model incorporating the kinetic theory of granular flow, the momentum exchange between two different particle species should be accounted by the particle-particle drag. The parametric studies of the particle-particle friction coefficient in the Syamlal particle-particle drag model were performed to evaluate the particle frictional sliding effect during collisions on the segregation and mixing behavior of binary particle mixtures. The predicted jetsam concentration distributions were compared with the available experimental data in both the axial and radial directions. The results indicate that the particle frictional sliding behavior during collisions influences the segregation and mixing process in different ways. The particle frictional sliding effect during collisions should be accurately considered when modeling the hydrodynamics of binary particle mixtures, especially for the segregation process. Crown Copyright (C) 2014 Published by Elsevier B.V. All rights reserved.