Vegetable oils are increasingly being used as long-term carbon donors to stimulate reductive dechlorination of trichloroethylene (TCE). Besides potential enhancement of biodegradation, the addition of vegetables oils may impact TCE fate and distribution within the aquifer by acting as non-aqueous phase liquids (NAPL). Distribution coefficients for TCE between groundwater and four vegetable oils were determined using a slow-stir technique. Log vegetable oil/water distribution coefficients (log Kvw) were found to range from 1.0 to 2.56. TCE/vegetable oil distribution coefficients statistically increased with an increase in oil weathering while the concentration of dissolved organic carbon (DOC) in the water did not change over time. Copyright © Taylor & Francis Group, LLC.