In this paper, we demonstrate the fabrication of a highly sensitive, selective, reproducible and reliable amperometric sensor for cyanide ion in aqueous solutions based on PEG modified ZnS nanoparticles (NPs). The fabricated cyanide ion sensor exhibits a very high and reproducible sensitivity of similar to 79.7 mu A cm(-2) nM(-1) with a response time less than 2 s and a detection limit of 0.177 x 10(-6) mol L-1, which is similar to 16 times lower than maximum value of cyanide (2.7 x 10(-6) mol L-1) permitted by the World Health Organization (WHO) in drinking water. Moreover. various amperometric responses of some common interfering ions (Cl-, Br-, NO3-, SO42- and CO32-) have also been recorded which confirm that the fabricated sensor is highly selective. This work demonstrates a simple, easy and promising technique for the detection of highly toxic and deadly cyanide ion in aqueous medium. (c) 2012 Elsevier Ltd. All rights reserved.