CaO/Al2O3 catalytically transesterifies and cracks vegetable oils in the gas phase at temperatures beyond 400 degrees C. The products are biodiesel (fatty acid methyl esters) and hydrocarbons. Oil conversion was complete with excess methanol in the feed. The gas residence time was less than 1 s and the weight-hourly-space velocity in the capillary fluidized bed was on the order of 5 h(-1) (0.12 mg min(-1) oil feed rate with 1.6 g of catalyst). Periodic regeneration cycles with O-2 converted the coke on the catalyst to CO and CO2. Regenerated catalyst is initially less selective towards biodiesel. Coke preserves the active sites that are selective for the conversion of the triglycerides into biodiesel. The biodiesel yield was highest (44%) dosing the catalyst with oil for 5 min then regenerating it for 1 min. (C) 2015 Elsevier Ltd. All rights reserved.