Abstract An efficient gold decorated mesoporous silica/polymer hybrid nanoreactor was prepared for catalytic applications. The Huisgen cyclo-addition method was used to immobilize poly(2-(dimethylamino)ethyl methacrylate (PDMAEMA) gatings on the surface of the mesoporous silica using a ‘grafting-to’ approach. The catalyst particles exhibited well-ordered mesoporous structural integrity with well-dispersed gold nanoparticles showing resonance plasma absorption. The catalyst exhibited efficient peroxidase like activity for the oxidation of 3,3,5,5-tetramethylbenzidine in the presence of H2O2, which was found to be in consistent with the standard Michaelis-Menten kinetics. The change in the catalytic activity with temperature was evaluated using 4-nitrophenol reduction as the model reaction. The catalyst showed nonlinear variation of the rate constants with temperature. A sharp decrease in the rate constant was observed above 35 °C due to the thermodynamic volume phase transition of the grafted PDMAEMA chains. In contrast, a typical Arrhenius-type dependence of the rate constant on temperature was observed above and below the transition temperature of PDMAEMA.