Inhibition　and　recovery　of　the　catalytic　activity　of　bovine　serum　albumin-capped　gold　nanoclusters　(BSA-AuNCs)　is　observed　for　the　first　time　by　introduction　of　cysteine　and　Hg2+.　The　prepared　BSA-AuNCs　possess　highly　intrinsic　peroxidase-like　activity.　It　can　catalyze　the　oxidation　of　3,　3,　5,　5-tetramethylbenzidine　by　H2O2　to　produce　a　blue　colored　product.　Based　on　this　phenomenon,　a　new　colorimetric　assay　for　rapid,　selective　and　sensitive　detection　of　cysteine　and　Hg2+　in　aqueous　solution　has　been　demonstrated.　The　interaction　process　between　target　molecule　and　BSA-AuNCs　is　very　fast,　so　that　the　whole　test　can　be　completed　within　ten　minutes.　Moreover,　the　fabricated　colorimetric　sensor　is　simple　and　cost-effective,　without　the　need　of　nucleic　acid　based　recognition　element　and　complicated　washing,　separation　and　labeling　process,　thus　holds　great　promise　for　routine　analysis　of　cysteine　and　Hg2+　in　real　samples.　©　2015　Elsevier　B.V.　All　rights　reserved.