This study was aimed at an experimental set-up that allows the investigation of mass transport by means of the limiting current method in high aspect ratio microstructures under megasonic conditions. The main focus is the qualitative description of observed effects. We investigated mass transport rates at recessed rotating microstructured electrodes. They are dependant on the working electrode location, its construction and the electrical power applied to the transducer. Local heating at the working electrodes was observed, even when the cell temperature was held constant. The correlation between spatial distributions of sound pressure and limiting current was observed. Two components of megasonic effect can be distinguished: thermal and hydrodynamic. The ratio of these components depends on the electrode's construction. (c) 2007 Published by Elsevier Ltd.