The ’airlift’ phenomenon has been identified as having great potential in ensuring good mixing in both two-phase (gas-liquid) and three-phase (gas-liquid-solid) reactors. One approach to studying three-phase airlift (TPAL) reactors involves ’de-constructing’ the reactor into its constituent regions, and studying these in turn. In particular, in this study the riser region has been extensively studied using a purpose built Three-Phase Upflow Facility. This has provided direct measurements of the phase holdups and velocities for a range of gas-liquid-solid mixtures in cocurrent upflow. The solids velocity in turbulent three-phase upflow has also been directly measured and correlated in drift flux form. This is important since it has a direct bearing on the solids distribution between the riser and downcomer regions in a TPAL reactor. Using this new data, a semi-theoretical model is able to give good predictions of TPAL reactor hydrodynamic performance.