The electrodeposition of nickel onto rotating disc electrodes from chloride solutions under various conditions has been studied with the aim of establishing the mechanism of the electrode reactions which occur during deposition. The influence of various solution parameters on the current versus potential behaviour during deposition has been investigated. Since the deposition is accompanied by hydrogen evolution, the partial currents due to nickel deposition were required and were determined from the charge required to strip the deposit anodically. The results have been interpreted in terms of a mechanism in which the transfer of the first electron to the nickel(II) ion is rate-determining. Catalysis of the reaction by chloride ion has been interpreted in terms of participation of the monochlorocomplex in the rate-determining step. Comparison of these results with those obtained by other investigators and with the comparable reaction in sulphate solutions is made. The influence of various impurity cations on the current efficiency and purity of the nickel deposit has been studied and the current-potential behaviour interpreted in terms of anomalous codeposition of the impurity cations as alloys with the nickel.