An electrochemical sensor for dopamine was developed by electrodepositing poly(propylene imine) (PPI) dendrimer and gold nanoparticles (AuNPs) onto a glassy carbon electrode (GCE). Electrochemical characterisation of the sensor was carried out by cyclic voltammetry and electrochemical impedance spectroscopy in ferri/ferrocyanide electrolyte. The nanocomposite elec-trode (GCE-PPI-AuNPs) showed improved electroactive surface area and electrochemical response over bare GCE. The sensor recorded a detection limit of 0.16 μM over a concentration range of 0.1 μM to 125 μM. The sensor was applied for dopamine detection in human serum samples and in the presence of interfering substances such as ascorbic acid and epinephrine.