New methodology for the measurement of electrogenerated chemiluminescence (ECL) has been developed by using a pulse-electrolysis stopped-flow system. Using this method, the ECL from both energy sufficient and energy deficient chemical systems composed of different kinds of radical ions can be observed. In the reaction between the thianthrene cation radical and the pyrene anion radical, it was found that the emission spectra changed with the addition of the precursors, reflecting both complex electron and energy transfer processes in solution. In addition, the emitted spectrum was found to strongly depend on other molecules present when three species were mixed.