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The influence of ultrasonic irradiation on the electrochemiluminescence evolved from the electrochemical oxidation reaction of tris(2,2′-bipyridyl)ruthenium(II) chloride [Ru(bpy) 3 Cl 2 ] or tris(1,10-phenanthroline)ruthenium (II)chloride [Ru(phen) 3 Cl 2 ] in aqueous oxalate has been examined. Under the conditions described here, insonation resulted in an increase in the luminescence yield of over 100%, in a highly reproducible manner. These effects were found to result from ultrasonic irradiation and can be understood with reference to the changes in mass transport of reactants through the bulk solution and modification of the electrode Nernst diffusion layer that have been observed by other workers. A relationship between the light intensity and the square of the cell current was observed under various ultrasound powers, and it was found that this is consistent with the kinetic scheme proposed by Bard et al. for the electrooxidation reaction under silent conditions. This indicates that the reaction mechanism under insonation is consistent with that proposed for the silent reaction. The electrochemiluminescence spectrum under insonation was measured with greater precision than previously and was shown to be identical to that under silent conditions. Luminescence quenching by oxygen, problematic in earlier reports, was measured under insonation and also with greater precision than previously in the silent system. The Stern-Volmer relationship was obeyed under both sets of conditions, and oxygen quenching phenomena appear to be unaffected by insonation of the system.