Ag/Pd triangular nanoshells of different sizes are prepared for catalyzing electroless copper deposition. As supported by the analysis of quartz crystal microbalance and mixed potential theory, the alloy nanoshells can be successfully used as new activators and have the excellent activity for electroless copper bath. For a comparison of deposition rates with a system of triangular Ag/Pd nanoshells, the large Ag/Pd nanoshell is found to have the maximum activity toward electroless bath. (C) 2008 Elsevier Ltd. All rights reserved.