The electrodeposition of Cu-gamma-Al2O3 nanocomposites as thin films and into recessed electrodes prepared with X-ray lithography was examined in ammonia-citrate electrolytes. Partial current density, current efficiency and deposit particle concentration were determined with a rotating disk electrode. At pH 8 the presence of particles resulted in an enhancement of the Cu reaction rate, while at pH 10 the reaction rate appeared inhibited. The amount of particles in the deposit and current efficiency was larger for pH 8 than pH 10, rendering the pH 8 solution a more promising electrolyte to electrodeposit 500 mu m deep recesses for MEMS composite components. (c) 2006 The Electrochemical Society.