Hydrodynamics (e.g. gas holdup, bubble size, and flow regime) significantly influences the performance of slurry bubble column reactors. In this work, the influence of gas, liquid, and solid phase properties on the hydrodynamics was investigated at temperatures up to 573 K and pressures up to 0.5 MPa. Amongst the investigated liquids, the hydrodynamic behavior of ionic liquids at elevated temperatures is ruled by their high surface tension leading to small gas holdups and formation of large bubbles compared with heat transfer oils. The solids strongly influence the hydrodynamics but their effects are still not fully understood. Therefore, the behavior of solids was investigated in this work. The results indicate that small concentrations of fine particles reduce bubble coalescence and subsequently stabilize the homogeneous regime. However, the primary bubble size increases with the addition of solids. Furthermore, it has been shown that the gas holdup decreases with an increasing difference between particle and liquid density. (C) 2015 Elsevier B.V. All rights reserved.