We conducted a simultaneous measurement of the potential of Cu 2+ , oxidationreduction potential (ORP), and the chemiluminescence intensity in the luminol-H 2 O 2-KSCN-CuSO 4-NaOH system. Two types of chemiluminescence were identified: a very faint continuous chemiluminescence and a strong oscillating chemiluminescence. The correlation between the potential of Cu 2+ and ORP was measured experimentally for the first time. The effect of the initial concentrations of Cu 2+ and H 2 O 2 on the overall chemiluminescence intensity and the oscillation frequency was investigated in detail. Time-dependent concentration variation of the chemical species existing in the reaction system was calculated using a Runge-Kutta method. Two elementary chemical reactions not considered previously were taken into consideration. The overall experimental behavior was well explainable with our simulation. Based upon the comparison of our simulation with the experiment, we proposed that the strong oscillating chemiluminescence was induced by the reaction of luminol with ⋅OS(O)CN.