Copper nucleation and growth on titanium substrates from concentrated acidic copper sulfate solutions was studied at 45 and 65 degrees C and high cathodic potentials. Electrochemical experiments allied to SEM examination were performed to characterize the mechanism of nucleation and its evolution with time. Particular emphasis was given to the influence of potential and agitation on the initial stages of nucleation and growth. Results indicated that most of copper nucleation on titanium from a 83 g dm(-3) Cu2+ solution, at 65 degrees C, is achieved in a matter of milliseconds. As expected, the initial stages of the copper nucleation and growth is strongly dependent of potential and temperature, and the influence of agitation is only evident at very high potentials. The calculated diffusion coefficients for Cu2+ at 45 and 65 degrees C, under the experimental conditions, were found to be 9.16 x 10(-6) and 1.62 x 10(-5) cm(2) s(-1), respectively.