A low frequent inductive behaviour was observed while monitoring the electrodeposition of silver from thiosulphate complexes using ac-impedance spectroscopy. This phenomenon could not be explained by means of a formerly proposed chemical-electrochemical (CE) reaction mechanism. Numerical simulations are put forward for the identification of a more appropriate reaction mechanism. It is suggested that electrosorption steps and mass-transfer controlled kinetics play an important role. Therefore, as a preliminary study in this paper, those two phenomena are studied separately by means of two case study systems. It is examined how an interpretation by means of numerical outcomes compares to an analyses by means of analytical results. (c) 2005 Elsevier Ltd. All rights reserved.