The positive pole V(IV)/V(V) and negative pole V(II)/V(III) reactions in a vanadium redox flow cell have been investigated on a glassy carbon electrode by various techniques. Several parameters for these electrode reactions were obtained at high concentrations of both sulfuric acid and V species in addition to the mobility (diffusion coefficient and Stokes radius) of V(V), V(IV), V(III) and V(II) species. (C) 2004 Elsevier B.V. All rights reserved.