Cu-Zn alloy formation on a non-conductive epoxy substrate was demonstrated through successive electrochemical processes: (i) conventional electroless Cu deposition on the substrate using an aqueous bath, and (ii) electrochemical alloying of the resulting Cu layer with Zn using a reduction-diffusion (RD) method in a Zn2+-containing ionic liquid bath at 150 degrees C. The obtained Cu-Zn alloy layers were adhesive and were uniformly grown with maintaining the surface morphology of the initial electroless Cu. The Cu-Zn phases, i.e. gamma-Cu5Zn8, beta'-CuZn, and/or alpha-Cu(Zn), which define the color of the layers were dependent on applied potential during the RD alloying. Thermodynamics of the alloy formation was also discussed. (C) 2013 The Electrochemical Society. All rights reserved.