The effect of temperature on nickel electrodeposition from a nickel sulfamate electrolyte has been investigated. All the experimental points in a plot of nickel film thickness vs. current density collapse onto a single straight line irrespective of deposition temperature. A relation derived from the Butler-Volmer equation is successful in predicting cathode potential shifts caused by change of deposition temperature. Moreover, an interface width, which characterizes the roughness of the surface and is defined by the root mean square of fluctuation in the height, is shown to have a saturated value that is related to the deposition temperature. Thus, two kinds of activation energies for the charge transfer reaction and for grain growth are estimated from the temperature dependence of the cathode potential shift and the grain size.