Fine bubbles are a key component in improving the performance of gas-liquid reactors, particularly in situations where reactions are mass transfer limited. Many aerator types exist for different reactor applications; however conventional aerators are mostly suited to coarse bubble generation. A new aerator suitable for microbubble generation by fluidic oscillation has been designed and tested with the view of getting a uniform bubble distribution across the aerator. Microbubbles generated from various membrane pore sizes and oscillation frequencies were characterized for this aerator to determine the optimum operating parameters. It was evident that the introduction of a flow distributor plate to the plenum chamber improved gas distribution from the inlet to the porous membrane leading to uniform bubble generation across the entire aerator. The resultant average bubble size from this new design under oscillatory flow was found to be approximately 2-3 times the membrane pore size. This outcome has a great potential to promote the efficiency of multiphase reactors where mass transfer plays a key role. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.