Electrodeposition under continuous and pulsed regimes of nickel alloyed with manganese is investigated. Some physicomechanical properties of the electroplated layers - hardness, internal stress and plasticity - are determined. It is established that the application of pulsed current does not affect the amount of manganese included in the alloy, but strongly alters the properties of the deposited layers. The inclusion of manganese, as well its presence in the electrolyte, leads to the increase of internal stress and microhardness of the nickel layers and substantial decrease of plasticity. On the basis of the data obtained, suggestions are proposed for the possible mechanism of manganese inclusion in nickel layers.