The frequent simple gross redox reaction [Inline formula] notation, where A is a solution species and Bads is its adsorbed reduction product, is misleading in its simplicity. It may represent a concerted reaction, i.e., a true elementary step in which the electron transfer (ET) to the solution species A is concerted with the creation of the electrode-species bond(s) in Bads. Conversely, the reaction may be a composite one involving two sequential steps. One such two-step mechanism may be termed as a CadsEads sequence where Cads stands for a pre-adsorption elementary step and Eads for the follow-up ET. Alternatively, the two steps may proceed in the reverse order, leading to an EsolnCads mechanism in which A is reduced into B, both being solution species, followed by adsorption of B onto the electrode.The present theoretical investigations show that a different panel of voltammetric behaviours may be produced by each mechanism. Hence, rationalising voltammetric peak positions and shapes in terms of surface or potential effects is challenging and may be completely erroneous if the wrong mechanistic sequence is considered.