The special features of space-charge distribution were analyzed which arise within the diffusion layer while cations and a neutral substance are reduced in parallel under steady - state conditions and the negatively charged products of the electrode reaction subsequently undergo a homogeneous reaction. It was shown that at certain values of the parameters, the space-charge distribution can develop a peak in the center of the reaction zone of the homogeneous reaction. The distributions of potential and electric field were obtained for the system being examined.