The Beckmann rearrangement of cyclohexanone oxime to caprolactam has been studied in the vapor phase over fluorinated alumina catalysts containing 1 to 61 wt. % F. Addition of fluorine enchances the catalytic activity of Al2O3. Selectivity to caprolactam shows a maximum in the fluorine range 11–31%. It is likely that an optimum distribution of Lewis and Bronsted acidic sites on the catalyst surface is responsible for the high selectivity observed at intermediate fluorine contents. Addition of water to the gas phase causes a decrease in selectivity.