The anomalous codeposition of Zn + Co alloys on vitreous carbon, copper and nickel substrates in a chloride bath was studied. The results indicate that the substrate influences both the initial electrodeposition stages and the alloy formation. For the same electrodeposition conditions, vitreous carbon and copper substrates favour the formation of deposits richer in zinc than those obtained over a nickel substrate. In the stripping analysis of deposits obtained during anomalous codeposition, up to three major oxidation peaks were observed, the two corresponding to the more negative potentials are attributable to the zinc oxidation in the alloy and the more positive one to the oxidation of the remaining porous cobalt matrix of the alloy. Under our experimental conditions, two kinds of deposits have been analysed using X-ray diffraction (XRD). XRD analysis showed that deposits with very low cobalt percentage (less than 3%) and a hexagonal platelet structure had a distorted hcp zinc eta -phase. Polyhedral-grained deposits with between 4 and 10% cobalt were made up of quasi-pure zinc and a Zn + Co gamma -phase of bcc structure. A correlation between the stripping curve and the type of deposit has been found.