Successful design and scale-up of Slurry Bubble Column Reactors (SBCRs) require proper understanding of how operating conditions affect their flow behavior. Presently, there is little information on the flow dynamics of solids (e.g., distribution of velocities and turbulent parameters) in slurry systems that are operated at industrially relevant conditions of high pressure, high superficial gas velocities, and high solids loading. Computer Automated Radio Particle Tracking (CARPT) is widely recognized as one of a few techniques that can be reliably used even in highly turbulent and opaque slurry flows. This work utilizes an improved CARPT technique to investigate the effect of reactor pressure (0.1-1 MPa) and superficial gas velocity (0.08-0.45 m/s) on solids phase velocity and shear stress in a pilot scale 0.16 m diameter stainless steel column using an air-water-glass beads (150 mu m) system. The solids axial velocity and shear stress were found to increase noticeably with pressure and superficial gas velocity in the chum turbulent flow regime. (c) 2005 Elsevier Ltd. All rights reserved.