A novel heterogeneous magnetic nanocatalyst was designed by conjugating copper(II) ions with chitosan-bound magnetic nanocarrier. Its hydrolytic activity for phosphodiesters was evaluated by investigating the hydrolysis of secondary ester bis-(nitrophenyl) phosphate (BNPP) in aqueous media. The maximum hydrolysis rate of BNPP was observed around the pK(a) of nanocatalyst which was found to be 12. The kinetic studies revealed that the binding affinity of BNPP to the copper(II)-chelated chitosan magnetic nanocarrier was low as compared to other catalyst systems. However, the rate constants (k(cat)) and maximum reaction rate (V(max)) were found to be higher with lower activation energy for the developed nanocatalyst. Moreover, the developed nanocatalyst was magnetically recoverable and also had good reusability. (C) 2009 Elsevier Ltd. All rights reserved.