Understanding wood segregation in bubbling fluidized beds is of importance for the global analysis, comprehensive modeling, and scale-up of bubbling fluidized bed biomass gasifiers. This study presents measurements of voidage and segregation taken during experiments in fluidized beds containing inert materials mixed with biomass particles, The features of the wood particles affect the bed axial homogeneity; a small particle size or a high density increase homogeneity. When gas fluidization velocity is low, the biomass particles are more segregated from olivine compared to the results achieved with larger velocities. In all experiments, a significant portion of the wood remains within the bed (50-80%), while the rest of the biomass floats at the bed surface. The experimental modeling accurately represents the voidage of the bed, with the exception of the upper part of the bed and the floating portion of the biomass particles. The results of the present study are in agreement with recent publications. (C) 2015 Elsevier B.V. All rights reserved.