The inclined rotating tubular fixed bed reactor has been introduced recently as a novel reactor concept for multiphase processes, especially for heterogeneously catalyzed gas-liquid reactions with a mass transfer limitation of the gas phase (Harting et al., 2015; DOI: http://dx.doi.org/10.1016/j.ces.2015.02.008). It is based on the adjustment of a beneficial gas-liquid distribution in the cross section of the fixed bed that allows for complete utilization of the fixed bed accompanied by periodic wetting and draining of the catalyst. The hydrodynamics in gas-liquid co-current downflow are studied by applying a compact gamma-ray computed tomography system for different organic liquids and gas phase properties as well as various fixed bed packing materials. Four different flow regimes with stratified, sickle, annular and dispersed flow patterns are identified. Pressure drop and liquid saturation are presented as a function of reactor inclination and rotation. Inclination of the reactor is applied to force phase separation and the superimposed rotation of the clamped fixed bed results in a favorable wetting intermittency via periodic catalyst immersion. A significant rate enhancement of the hydrogenation of alpha-methylstyrene to cumene under severe limitations of the mass transfer of the gas phase is observed in the novel reactor concept at separated flow conditions. In addition, the potential for an efficient quenching of hotspots for exothermic reactions is demonstrated. (C) 2015 Elsevier B.V. All rights reserved.