Homogenous and crack-free Co-Mo films have been prepared by electrochemical deposition. The composition of the films was adjusted by varying MoO42- concentration, pH values and applied potentials. The magnetic properties of the Co-Mo films have been studied. The Co-Mo film with 18 at.% Mo has the highest saturation magnetization of 205 emu/g. The Co3Mo film with a hexagonal close-packed structure shows the largest coercivity. The electro-catalytic activity of the Co-Mo films has also been studied via hydrogen evolution reaction. Electrochemical tests in 1 mol L-1 NaOH solution demonstrate that the Co-Mo films have both good electro-catalytic properties and corrosion-resistance. (c) 2013 Elsevier Ltd. All rights reserved.