The deposition behaviour and morphology of Ni-SiC electro-composites were investigated under a triangular waveform. It was found that the grain size of the Ni-SiC composites decreased with increasing average current density, and the hardness of the composites increased with decreasing nickel matrix grain size. An equivalent circuit model based on the results of electrochemical impedance spectroscopy was formulated to simulate the charge transfer process under triangular waveform. Compared with deposits produced under the direct current, the triangular waveform with relaxation time provided a higher instantaneous peak current for charge transfer, which resulted in an improvement in morphology and hardness of the composites. The mathematical model was found to be in agreement with the experimental results. (c) 2004 Elsevier B.V. All rights reserved.