Mass transport is of critical importance during electroforming of LIGA microstructures, since different concentration profiles result in gaps of different lateral sizes. Two specially designed microelectrodes were manufactured and demonstrated to be suitable for the systematic investigation of the mass transport during electroforming in microstructures. The Rotating Microstructure Electrode (rme) facilitates investigations under well defined hydrodynamic conditions. Limiting current densities were measured in a redox electrolyte with Rotating Microstructure Electrodes and compared to results of a disc electrode rotating at the same rates. The Microstructure pH Electrode (mpe) allows pH values to be measured near the cathode in microstructures, within the diffusion layer, during nickel electroplating. The slope of the resulting pH gradient decreases with the growth of the deposit.