A novel, continuous, oscillatory flow screening mesoreactor, composed of tubes with smooth periodic constrictions, is presented as a new option for small-scale reaction engineering applications, particularly those involving the screening of solid catalysts. Experimental studies using particle image velocimetry have demonstrated that this reactor provides good fluid mixing, and is able to suspend catalyst particles with a wide range of sedimentation velocities. Results from 2D and 3D CFD simulations exhibit semi-quantitative agreement with the experimental data, and will aid in the design of future reactors. Potential application areas for this reactor are specialist chemical manufacture and high-throughput screening. Unlike conventional screening devices, the flow patterns in this reactor can be reproduced at larger scales, therefore, results in the laboratory can be related directly to larger scale production.