Voltammetry measurements were performed on iron powder particles of various size fractions immobilized on the surface of a paraffin-impregnated graphite electrode in electrolytes of various pH values. The course of voltammetric curves implies that the start of the dissolution process is shifted negatively with increasing pH value and the anodic dissolution process of iron is inhibited due to adsorption of products of the electrode reaction on iron particle surfaces. The rate of dissolution is changed also with iron particle size: decreasing dissolution rate and appearance of inhibition were encountered with an increase in particle size. A mechanism was suggested taking into account the influence of both pH of the electrolyte and particle size fraction. Electrochemical dissolution of freshly reduced iron from the solution proceeds at a lower potential than the same process of iron powder immobilized on the electrode.