The time-resolved thermal lens and the pulsed photoacoustic techniques have been used to determine the thermally averaged charge transfer excited state energy of Ru(bpy)32+ in ambient aqueous solutions. The averaged excited state energy of ((3MLCT)Ru(bpy)32+) was found to be (16.8 +/- 0.2) x 10(3) cm-1 by the photoacoustic method and (17.0 +/- 0.6) x 10(3) cm-1 by the thermal lens method. These measurements indicate that the difference between the effective molar volumes of the ground and charge transfer excited states is very small.