The cobalt sulfide (Co9S8) nanoparticles (NPs) have been synthesized by the solvothermal techniques by utilizing Cobalt diethyldithiocarbamate (CoDTC2) as single-source precursor and hexadecylamine (HDA) as shape directing agent. As-prepared Co9S8 NPs were characterized with structural, morphological, thermal, Spectroscopic and surface analysis using PXRD, TEM, SEM-EDS, TG/DTA, FTIR, Raman and XPS studies respectively. The electrochemical performances were investigated by galvanostatic charge-discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) analysis with Co9S8 NPs modified working electrode. The Co9S8 NPs modified electrode delivered excellent specific capacitances of 502 Fg-1 at current densities of 1 Ag-1. The capacitance retention of Co9S8 was found to be 87% over the examination even after 7000 cycles. Furthermore, a hybrid supercapacitor (HSC) device assembled with cathode and anode materials delivers a high energy density of 15.47Whkg-1 with power density of 1274.9Wkg-1. Display omitted •Co9S8 nanoparticles have been successfully synthesized by simple solvothermal reflex method.•PXRD and SEM exhibit the cubic crystalline structure and spherical-like morphology for Co9S8 nanoparticles.•Co9S8 electrode material exhibits Faradic pseudo capacitive behaviour.•An enhanced high specific capacitance of 502 Fg-1 and current density of 1 Ag-1.•The Co9S8 electrode material exhibits 87% energy retention in cyclic test after 7000 cycles.