The voltammetric lability of a complex system, where a metal ion M and a ligand L form the species ML and ML2, is examined. Together with the rigorous numerical simulation of the problem, two limiting cases are analysed for the overall process ML2 --> M: (i) the most common case for aqueous complexes, where ML --> M is the kinetically limiting step and (ii) the case where ML2 --> ML is limiting. In both cases, analytical expressions for the lability criteria are provided which show good agreement with the results obtained from the rigorous numerical simulation of the problem. (C) 2004 Elsevier B.V. All rights reserved.