Abstract The knowledge of gas holdup, liquid recirculation and turbulent parameters is important for design and performance calculation of bubble column reactors. Although numerous experimental studies have been reported on this subject, most are point measurements limited to columns without internals operated at low gas velocities. In this study, we present the results obtained for the gas holdup profiles, time-averaged liquid velocity profiles, turbulent stresses and eddy diffusivities (radial and axial) obtained in a 18″ (44 cm) diameter column without and with internals similar to those used in industrial scale units (e.g., heat exchanger tubes) using both air/water and air/drakeoil 10 (viscosity ∼30 cP) at gas superficial velocities of 2, 5 and 10 cm/s. The scale-up procedure suggested by Degaleesan (1997) is critically examined in light of these results.