The liquid residence time and the backmixing in an inclined rotating tubular fixed bed reactor operated with gas-liquid co-current downflow are studied experimentally. This novel reactor concept is introduced to extent the process intensification strategies of chemical multiphase reactors. The intermittent catalyst immersion due to rotation induces a continuous refreshment of the liquid at the catalyst surface and enhances the access of the gas phase to the catalyst in the drained section of the fixed bed. Depending on inclination angle and rotational velocity, different flow regimes are observed. In particular, the flow regimes with stratified gas-liquid flow can be utilized to enhance the performance of the reactor for heterogeneous catalytic reactions. The backmixing study is based on the method of the imperfect tracer pulse and the propagation of the tracer is measured by low-intrusive wire-mesh sensors. Compared to conventional trickle bed reactors, liquid residence time and axial dispersion are increased by the inclination and rotation. The effects of reactor inclination angle and rotational velocity as well as of particle size and liquid superficial velocity on the liquid backmixing in the inclined rotating tubular fixed bed reactor are shown in detail. (C) 2015 Elsevier B.V. All rights reserved.