A glassy carbon electrode (GCE) modified with cobalt(II) meso-tetraphenylporphrine/multiwall-carbon nanotube (CoTPP/MWNT) was applied to investigate the electrochemiluminescent (ECL) behavior of luminol. The ECL intensity of luminol was found to be increased greatly on this modified electrode. The presence of cobalt(II) meso-tetraphenylporphrine (CoTPP) can catalyze the reduction of oxygen on the electrode surface to produce HOO-, which can increase the ECL intensity of luminol. Moreover, MWNT can provide the more effective area of the electrode, and can act as a promoter to enhance the electrochemical reaction. The proposed method enables a detection limit for luminol of 1.0 X 10-8 mol/L in the neutral solution. Under the optimum condition, the enhanced ECL intensity of luminol by H202 had a linear relationship with the concentration of H202 in the range of 1.0 X 10-7 to 8.0 x 10-8 mol/L with the detection limit of 5.0 x 10-9 mol/L. (c) 2008 Elsevier Ltd. All rights reserved.