Nano-alumina particles (80 nm) are easily agglomerated into larger particles in a nickel sulfamate bath with an average diameter of about 1109 nm. This leads to low alumina content in the composite coating. In this study, the diameter of alumina agglomerates was reduced with the decrease in electrolyte concentration. Alumina agglomeration was reduced to 178 nm at a bath concentration of 0.20 M nickel ions under 5 W l(-1), with 40 min ultrasonic energy treatment. Effective alumina particle dispersion in the electrolyte solution creates more opportunities for loose and strong adsorption of alumina particles onto the electrode. The Ni/Al2O3 composite coating was prepared with electrolyte concentration variations under reasonable electrochemical conditions. The alumina particle volume content in this composite coating was increased from 8.37 vol.% to a maximum value of 26.78 vol.%. The homogeneity of the composite coating is promoted with effective dispersion. (C) 2004 Elsevier B.V. All rights reserved.