Sorption partition coefficients between water and organic carbon (K o c ) for deuterated benzene, toluene, and ethylbenzene have been estimated by measuring values of the octanol-water partition coefficient (K o w ) and HPLC retention factors (k ), which correlate closely to values of K o c . Measured values of log K o w for non-deuterated and deuterated toluene are 2.77 (± 0.02) and 2.78 (± 0.04), respectively, indicating that within experimental error, log K o c for deuterated and non-deuterated toluene are the same. The HPLC method provides greater precision, and yields values of Δ log K o c (= log K o c [deuterated] - log K o c [non-deuterated]) of -0.021 (± 0.001) for benzene, -0.028 (± 0.002) for toluene, and -0.035 (± 0.003) for ethylbenzene. The small values of Δ log K o c demonstrates that deuterated compounds are excellent tracers for the hydrologic behavior of ground water contaminants.