Polymeric dinuclear alkynylcopper(I) complexes, for example phenylethynylcopper(I), can be prepared by a robust method involving the interaction of terminal alkynes with copper(II) salts in acetonitrile. The use of the ladder polymers provides heterogeneous catalysts for copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions and provides important mechanistic information.