<p>In this work, CuO nanospheres rGO composites (CuO-rGO) was used as electrode materials for supercapacitor and glucose sensor applications. The CuO-rGO was synthesized by simple mixing the CuO and rGO obtained by simple sol- gel precipitation procedure followed by calcination of Cupric salt precursor and rGO using chemical reduction of GO. As synthesized CuO-rGO were characterized by p-XRD, FT-IR, Raman and SEM studies. The SEM studies confirm the spherical morphology of the CuO nano structures. The capacitor studies of the CuO-rGO composites were studied using the CV, GCD and EIS techniques and about 300.81 F g⁻¹ of capacitance was observed with 0.1 A g⁻¹ current rate and about 97% capacitance was retained after 500 cycles. The high specific capacity of CuO-rGO composites, are due to the unique homogeneous spherical morphology of the CuO nano structures, high conducting nature of the rGO and synergetic effects of the composites. Furthermore, CuO-rGO modified GCE exhibits good electrocatalytic oxidation for glucose and the limit of detection (LOD), limit of quantification (LOQ), sensitivity and dynamic linear range obtained with CuO-rGO modified GCE were 0.914&#xa0;µM, 0.0315&#xa0;µM 50.52 µA µM⁻¹&#xa0;cm⁻² and 1.0 to 6.0&#xa0;µM respectively. The glucose sensing ability of CuO-rGO modified GCE in serum samples were satisfactory done and compared with standard clinical methods. This suggests that the CuO-rGO composites have great potential for energy storage and electrochemical sensing device applications.</p>