Diamond has long been of interest as a biomaterial due to its expected biocompatibility and chemical stability. Progress in surface functionalization of diamond and diamond electrochemistry has extended this interest to use as a biosensor platform. The sensitivity and selectivity of the diamond surface can be enhanced by covalently attaching carbon-based biochemicals. In this communication, an amine-thiol molecule was attached to a boron-doped diamond (BDD) surface to produce an enhanced ability to detect NO species. In the case of hydrogen terminated BDD, it was found that NO (aqueous) oxidation was insufficiently distinct to electrochemically detect NO. However, the amine-thiol functionalized BDD surface provided a distinct oxidation peak from 65 nanomolar to 236 nanomolar concentrations. Multiple cyclic voltammagrams with amine-thiol functionalized BDD electrode in (HPLC-quality) purified water indicated that the covalently attached surface molecules resisted decomposition during both anodic and cathodic polarization. (C) The Author(s) 2015. Published by ECS. All rights reserved.