Three of the fundamental variables in voltammetry are the faradaic current I(t) and the surface concentrations c(R)(s) (t) and c(P)(s) (t) of the reactant and product. This article explores the relationships between these variables for cases in which the surface concentrations are uniform. Convolutions are derived which permit interconversion between the current and the surface concentrations. Examples are presented that apply to various electrode geometries, with and without the participation of homogeneous kinetics. An intriguingly simple connection is established between the convolution required for the I(t)--> c(s) (t) conversion and that applicable to the converse c(s)(t)--> I(t) transformation. These operations may be exploited in modelling voltammetric experiments and several exemplars are developed.