The biexcitonic annihilation of triplet products of ion recombination is incorporated in the kinetic description of electrochemiluminescence. This process resulting in excitation and fluorescencence of singlets is the dominant mechanism of the initial quenching of triplets, while their concentration is still high. Therefore, the contribution of triplets in subsequent phosphorescence is never as high as expected even at a large exergonicity of inter-ion electron transfer when the recombination to the triplet state prevails on recombination to the ground state of neutral products. The kinetics and quantum yields of fluorescence and phosphorescence are calculated by means of integral encounter theory. © 2001 American Institute of Physics.