Core-shell structured particles were prepared from carbonized zeolitic imidazolate frameworks (ZIFs) and reduced graphene oxide (rGO). The particles possess a nitrogen content of up to 10.6%. The loss of nitrogen from the ZIF is avoided by utilizing the reduction and agglomeration of graphene oxide with suitable size (>2 mu m) during pyrolysis. The resulting carbonized ZIF@rGO particles were deposited on a glassy carbon electrode to give an amperometric sensor for H2O2, typically operated at a voltage of -0.4V (vs. Ag/AgCl). The sensor has a wide detection range (from 5 x 10(-6) to 2 x 10(-2) M), a 3.3 mu M (S/N = 3) detection limit and a 0.272 mu A.mu M(-1.)cm(-2) sensitivity, much higher than that of directly carbonized ZIFs. The sensor material was also deposited on a screen-printed electrode to explore the possibility of application.