Polyhedrons shaped three dimensional cobalt oxide (Co3O4 PHs) particles were synthesized via simple and facile hydrothermal synthetical route. The morphological, elemental, diffraction and electrochemical studies have been performed to verify the structure and shape. The Co3O4 PHs possesses good porosity, large electrochemical area, roughened surface, and stable electrochemical behavior. The Co3O4 PHs modified electrode was fabricated which displayed excellent electrocatalytic ability toward 4-nitrophenol (4-NP). A rapid, sensitive, selective, reproducible, and durable electrochemical 4-NP assay, by employing Co3O4 PHs modified electrode was described. The sensor displayed outstanding sensitivity with nanomolar limit of detection of 4.09 nM, which surpassed the detection limits of many previously reported sensors. The practical applicability of the sensor was successfully demonstrated in rapid in drinking water, which showed good recoveries. The facile synthetical route, easy fabrication and outstanding sensing attributes make this modified electrode as potential candidate in environmental analysis of 4-NP. (C) 2017 The Electrochemical Society. All rights reserved.