The dehydration of lesquerella oil has been accomplished for the first time. Dehydration was performed using sulfuric acid, sulfates and phosphates, acidic clay, and aluminum oxide as dehydration catalysts. Dehydration products were characterized by infrared (FTIR), ultraviolet (UV), and proton nuclear magnetic resonance (H-1-NMR) spectroscopies. Color grades, acid values, hydroxyl values, and iodine values were obtained by established ASTM methods. Dehydration of either lesquerolic or ricinoleic acids creates slightly more conjugated diene than nonconjugated diene. Product mole ratios of conjugated to nonconjugated diene versus catalyst type varied from 1.1 to 1.6. Dehydrated lesquerella oil containing about 28 mol % conjugated (77.8 mol % total) diene has an iodine value of 147. Drying properties were also examined. Dehydration converts nondrying lesquerella oil into a drying oil with a drying velocity equivalent to a commercially dehydrated castor oil.