Cohesion may have a significant effect on particle fluidization. Strong cohesive forces may result in a non fluidized bed of particles. The effect of cohesive forces mainly depends on the magnitude of the forces and the particle weight. Geldart's classification places materials into four groups based on particle diameter and density difference between the particles and the fluid. Each group has different fluidization characteristics caused by the cohesive forces: specifically, in Geldart's experiments, these were Van der Waals forces (VdWFs). This study presents an investigation of the cohesive forces in fluidized beds. Using Geldart's classification, it attempts to predict the classification of moist particulate materials, affected by the liquid bridge forces (LBFs) and fluidized in air. In order to do so, a model which calculates the LBFs was developed. The classification of the wet particles is predicted by calculating an equivalent diameter and using it in the Geldart chart. (C) 2019 Published by Elsevier B.V.