This investigation was focused on the influence of polymer hydrophilicity on the morphological structure and mechanical properties of copper-in-polymer gradient composite films (CPGCFs). The ion motion and reduction in swelling cathode films under an electric field were the core of the gradient morphology formation of a metal region in the polymer matrix. The morphological study of CPGCFs revealed that the hydrophilicity of poly(vinyl alcohol) was helpful in forming a continuously deposited layer. The nanoclusters (40 nm) aligned into a branchlike form in the copper-rich region in the poly(vinyl alcohol) matrix. On the basis of the fuzzy interface between the poly(vinyl alcohol) matrix and copper nanoclusters, a complex interaction between them was inferred. The reduced copper affected the mechanical properties of CPGCFs. The maximum load of CPGCFs could be enhanced by 25% to 167.0 N with optimal electrochemical reduction, but the elongation was depressed. An excess of reduced copper in the polymer matrix reduced both the strength and elongation of CPGCFs. The moduli of related samples showed trends similar to those of the strength. (C) 2004 Wiley Periodicals, Inc.