A　new　signal　amplification　strategy　for　sensitive　electrochemical　determination　of　tetracycline　(TC)　was　developed　by　using　platinum-catalyzed　hydrogen　evolution　reaction　(HER)　on　an　anti-TC　antibody-modified　immunosensor.　To　construct　such　a　HER,　platinum　nanoparticles　were　initially　deposited　to　graphene　nanosheets,　and　the　as-synthesized　platinum/graphene　nanosheets　(PtGN)　were　then　used　for　the　labeling　of　tetracycline-bovine　serum　albumin　conjugates　(TC-BSA).　With　a　competitive　immunoassay　format,　the　resulting　immunosensor　was　immersed　into　a　platinum　developer　solution　containing　1.0　mM　PtCl42-,　0.1　M　formate　(reductant)　and　0.5%　Tween　80　(pH　6.5)　to　promote　the　platinum　growth.　The　amplified　electrochemical　signal　mainly　derived　from　the　platinum-catalyzed　HER　in　an　acidic　medium　containing　10　mM　HCl　and　1.0　M　KCl.　Two　labeling　methods　and　assay　protocols　including　Pt-labeled　TC-BSA　and　PtGN-labeled　TC-BSA　with　or　without　the　platinum　enhancement　were　investigated　for　determination　of　target　TC,　respectively,　and　improved　analytical　features　were　obtained　with　graphene　nanosheets　and　platinum　growth　mechanism.　With　PtGN-labeled　TC-BSA,　the　effects　of　incubation　time　for　antigen-antibody　reaction　and　deposition　time　of　platinum　on　the　currents　of　the　immunosensors　were　also　studied.　The　strong　attachment　of　TC-BSA　to　the　PtGN　resulted　in　a　good　repeatability　and　intermediate　precision　down　to　9.8%.　The　dynamic　concentration　range　spanned　from　0.05　ng/mL　to　100　ng/mL　tetracycline　with　a　low　detection　limit　of　6　pg/mL　at　the　3s　blank　level.　In　addition,　the　methodology　was　further　validated　with　tetracycline　spiked　samples　including　honey,　milk　and　peanut,　and　the　recoveries　were　86-118%.　©　2013　Elsevier　B.V.　All　rights　reserved.