Picosecond absorption spectroscopy is utilized in determining the dynamics of proton transfer within a variety of substituted benzophenones/N,N-diethylaniline contact radical ion pairs in the solvents benzene and cyclohexane. A correlation of the rate constants with change in free energy for the reactions reveals an "inverted region" for proton transfer. This kinetic behavior is consistent with nonadiabatic proton transfer theories suggesting that the reaction involves proton tunneling at ambient temperatures.