Interactions between the MLCT excited states of RU(bpy)(3)(2+) (bpy = 2,2＇-bipyridine) or RU(bpz)(3)(2+) (bpz = 2,3＇-bipyrazine) and phenol or monochlorophenols have been investigated in aqueous solution using steady state and time-resolved spectrofluorimetry. The presence of phenol (PhOH), which does not quench *Ru(bpy)(3)(2+) in mildly acidic solution, causes the emission to undergo a blue shift with increasing [PhOH]; the emission quantum yields and the excited-state lifetimes decrease with increasing [PhOH] at low temperatures (5-35 degrees C) but increase with increasing [PhOH] at higher temperatures (35-70 degrees C). This behavior is understood in terms of the variations in the rate constants of the temperature-independent radiative and nonradiative decays of *Ru(bpy)(3)(2+) and the activation-controlled population of the metal-centered excited state as [PhOH] is changed. The presence of chlorophenols has no effect on the photophysics of *Ru(bpy)(3)(2+); PhOH reductively quenches *Ru(bpz)(3)(2+).