Herein,　we　describe　a　new　method　for　the　detection　of　hydrogen　peroxide　(H2O2)　in　food　by　using　an　electrochemical　biosensor.　Initially,　ultrafine　gold　nanoparticles　dispersed　on　graphene　oxide　(AuNP-GO)　were　synthesized　by　the　redox　reaction　between　AuCl4-　and　GO,　and　thionine-catalase　conjugates　were　then　assembled　onto　the　AuNP-GO　surface　on　a　glassy　carbon　electrode.　With　the　aid　of　the　AuNP-GO,　the　as-prepared　biosensor　exhibited　good　electrocatalytic　efficiency　toward　the　reduction　of　H2O2　in　pH5.8　acetic　acid　buffer.　Under　optimal　conditions,　the　dynamic　responses　of　the　biosensor　toward　H2O2　were　achieved　in　the　range　from　0.1μM　to　2.3mM,　and　the　detection　limit　(LOD)　was　0.01μM　at　3sB.　The　Michaelis-Menten　constant　was　measured　to　be　0.98mM.　In　addition,　the　repeatability,　reproducibility,　selectivity　and　stability　of　the　biosensor　were　investigated　and　evaluated　in　detail.　Finally,　the　method　was　applied　for　sensing　H2O2　in　spiked　or　naturally　contaminated　samples　including　sterilized　milk,　apple　juices,　watermelon　juice,　coconut　milk,　and　mango　juice,　receiving　good　correspondence　with　the　results　from　the　permanganate　titration　method.　The　disposable　biosensor　could　offer　a　great　potential　for　rapid,　cost-effective　and　on-field　analysis　of　H2O2　in　foodstuff.　Copyright　©　2011　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim.