Despite the mainly inhomogeneous and unstructured nature of linear polymers, the CuII complex of a vinylpyridine-acrylamide copolymer exhibits very efficient 2-electron catalysis toward the oxidation of catechol and derivatives to form quinones with and without 80 mM (0.27 %) H2O2, showing remarkable (0.114–2.67) × 105 and (2.83–9.60) × 104-fold rate enhancements, respectively, in terms of first-order rate constant relative to auto-oxidation of the substrates in an aqueous environment under mild conditions. Metal-binding profiles suggest the presence of cooperativity in the catalysis. The oxidation catalysis is inhibited by the di-copper tyrosinase specific kojic acid. Moreover, electron paramagnetic resonance spectra reveal magnetic interaction of the CuII ions. On the basis of the results, the catalysis by this CuII-polymer seems to be consistent with the mechanism of type-3 di-copper oxidases. This complex also shows effective single- and double-stranded DNA cleavage in the presence of 1.0 % H2O2. These studies suggest this CuII-polymer complex can serve as a unique “chemical nuclease” and a versatile chemical system for further exploration of Cu–oxygen chemistry. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)