The processes involved in the reduction of an electrolytic manganese dioxide (EMD) were investigated and their exchange current densities were determined. The dQ/dE vs E curve was fitted by least squares minimisation with peaks based on the Nernst equation. The derivation of the peak model is described. In the potential range of 0.3 to - 0.4 V (vs Hg/HgO reference), nine processes were found to contribute to the overall reduction. Exchange current densities for three of the main processes were determined from the movement of the deconvoluted peaks during a series of constant current discharge experiments.