Water, in its subcritical state, can be used as both a solvent and reactant for the hydrolysis of triglycerides. In this study, soybean, linseed, and coconut oils were successfully and reproducibly hydrolyzed to free fatty acids with water at a density of 0.7 g/mL and temperatures of 260-280 degrees C. Under these conditions the reaction proceeds quickly, with conversion of greater than 97% after 15-20 min. Some geometric isomerization of the linolenic acids was observed at reaction temperatures as low as 250 degrees C. Reactions carried out at higher temperatures and pressures, up to the critical point of water, produced either/or degradation, pyrolysis, and polymerization, of the oils and resultant fatty acids.