A voltammetric sensor for the simple and rapid determination of dopamine (DA) has been developed using a glassy carbon electrode modified with cobalt nano/poly (4-amino-3-hyroxy-1-naphthalenesulfonic acid) composite. On square wave voltammetric mode, the modified electrode was found to efficiently catalyse the electrochemical oxidation of DA in 0.1 M PBS (pH 7). Response of DA increased linearly with its concentration in the range 5 x 10(-5) M to 5 x 10(-7) M with a limit of detection (LOD) 1.75 x 10(-8) M. Reliability of the developed sensor in real sample analysis was ascertained successfully by determining DA in artificial blood serum, urine and cerebrospinal fluid (CSF). (C) 2018 The Electrochemical Society.