A corrugated plate reactor configuration was developed and assessed using 4-chlorophenol degradation experiments and mass transfer tests. Two other reactor systems, a flat plate reactor and a slurry reactor, were examined for comparative purposes. The corrugated plate reactor was found to be up to 150% faster and more energy-efficient than a similar flat plate reactor. Its electrical energy per order of concentration reduction (EE/O) was estimated to be as low as 37 kWh/m(3) and was close to that of a slurry system. Mass transfer rates in corrugated plate reactors were found to be up to 600% higher than those in the flat plate reactor. The superior performance of this reactor is due primarily to its large illuminated catalyst surface area per unit volume, and its ability to effectively deliver both photons and reactants to the catalyst surfaces. (C) 2004 Elsevier B.V. All rights reserved.