AbstractThe behavior of bubbles in a cocurrent gas‐liquid‐solid fluidized bed was investigated in a column of 76.2 mm ID in this study. The particles used were glass beads of 3 and 6 mm and a binary mixture of these particles. A novel dual electrical resistivity probe system was developed and utilized to obtain bubble properties including bubble size and rise velocity. The distributions of the bubble properties in the gas‐liquid‐solid fluidized bed were evaluated for three flow regimes: the dispersed bubble flow regime; the coalesced bubble flow regime; and the slug flow regime.