A simple and sensitive method for the determination of propranolol using a modified carbon paste electrode with graphene/Co3O4nanocomposite was presented. The electrochemical measurements of propranolol are studied using differential pulse voltammetry, cyclic voltammetry and chronoamperometry. The graphene/Co3O4nanocomposite exhibits excellent catalytic activity towards the electrochemical oxidation of propranolol in phosphate buffer solution of pH 7.0. The graphene/Co3O4nanocomposite facilitates the determination of propranolol in the concentration range 1.0–300.0 μM and a detection limit and sensitivity of 0.3 μM. and 0.1275 μA/μM were achieved.