The instantaneous and time-averaged heat transfer coefficients in the regions near the wall and at the center and average gas holdups were measured in a 0.28 m diameter slurry bubble column for the air-water and air-water-glass beads (35 mu m) system. The effects of high gas velocities (up to 0.35 m/s) and high, solids concentrations (up to 40 vol %) were investigated. Gas holdup decreased with increasing slurry concentrations; the rate of decline was rapid at high gas velocities. The instantaneous local beat transfer measurements were analyzed to study the bubble behavior in the regions near-the wall and at the center for different solids concentrations. Larger bubbles were detected in the wall region in slurry systems compared to the solid-free system. The average heat transfer coefficient decreased with increasing slurry concentrations, The heat transfer coefficient was always lower at the wall than at the center.