Industrial catalyst development is benefiting from the use of high throughput research. This is typically accomplished by running large numbers of experiments in parallel, using common reactant feed manifolds and analytical systems. In order to fit within a reasonable laboratory footprint, high throughput reactors must be small, yet retain mass and heat transfer rates that allow gradientless operation. For heterogeneous catalytic reactions there are a number of high throughput systems available for testing powdered, or granular catalysts in banks of plug flow reactors, but no reports of CSTR systems capable of testing formed catalyst particles used in commercial fixed bed reactors. We describe the development and engineering characterization of a small prototype CSTR for testing whole catalyst particles. The reactor has inside dimensions of 6.35 cm diameter by 2.8 cm deep and shows well-mixed behavior, based on methane tracer studies. Sublimation of non-porous cylindrical naphthalene cylinders (7.5 mm diameter by 7 mm long) was used to characterize the solid-gas mass transfer coefficient. It was found that the prototype reactor exhibits mass transfer rates similar or higher than reported in the literature for the much larger traditional Carberry and Berty-style reactors. This makes the new device suitable for further development of high throughput arrays of CSTR5 for testing commercial catalyst pills. (C) 2016 Elsevier Ltd. All rights reserved.