The present invention pertains to a process for regenerating and rejuvenating a used additive-based catalyst comprising the steps of regenerating the catalyst by contacting it with an oxygen-containing gas at a maximum temperature of 500°C, followed by rejuvenating the catalyst by contacting it with an organic additive, if necessary followed by drying at such a temperature that at least 50 % of the additive is maintained in the catalyst. Preferably, the maximum catalyst temperature during the regeneration step is 300-500°C, more preferably 320-475°C, even more preferably 350-425°C. The process according to the invention makes it possible to restore the activity of a used additive-based hydrotreating catalyst to its original level, or even to improve it to above that level.