The electrochemical behavior of atenolol. carvedilol and propranolol was investigated on copper-oxide nanoparticle modified carbon paste electrodes. The process of oxidation and its kinetics were established by using cyclic voltammetry, chronoamperometry techniques and also steady state polarization measurements. The results revealed that copper-oxide nanoparticle promotes the rate of oxidation by increasing the peak current, so these drugs are oxidized at lower potentials. The apparent electron transfer rate constant (K-s) and transfer coefficient (a) were determined by cyclic voltammetry and were approximately 7.1 s(-1) and 0.49, respectively. The modified electrodes showed excellent catalytic activity towards the oxidation of beta-blockers at an unusually positive potential in buffer solution. The linear concentration range of the proposed sensor for the atenolol, carvedilol and propranolol detection were 12-96, 5-37, and 10-104 mu M, respectively. (C) 2011 Elsevier Ltd. All rights reserved.