Abstract: A process and apparatus for rejuvenating particulate used catalysts in a single rejuvenation vessel and providing a rejuvenated catalyst material having properties that result in activity substantially equal to new catalyst. The pressurizable vertically-oriented vessel has inlet and outlet openings for the catalyst and washing liquids, and is arranged to facilitate successive solvent liquid washing, water washings, and acid treatment steps for the used particulate catalyst provided in a bed in the vessel conical-shaped lower portion which contains catalyst rotary stirring means. After rejuvenation of the used catalyst, it is withdrawn from the vessel conical-shaped lower portion downwardly through a central withdrawal conduit and control valve for further processing. The water-soluble solvent and acid treatment liquids can be usually recovered by distillation for reuse in the catalyst rejuvenation process.