The octanol-water partition coefficients of seven chlorobenzenes (1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,3,5-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,3,5-tetrachlorobenzene, pentachlorobenzene, and hexachlorobenzene) were measured by a conventional shake-flask, batch-contacting method over the temperature range (5 to 45)degrees C. The measurements at 25 degrees C in this study agree well with literature data obtained with comparable methods. The van’t Hoff plots of log K-OW versus T-1 exhibit linearity with values of K-OW increasing by 10%-14% over this temperature range. The enthalpy of phase change ranges from (17 to 24) kJ/mol. These temperature relationships can be incorporated into environmental models which predict the fate of chemicals in aquatic and terrestrial systems over a range of environmental temperatures.