The invention refers to a process for rejuvenating a hydrotreating catalyst comprising a group VIB hydrogenation metal and/or a group VIII hydrogenation metal, which comprises the steps of: (a) regenerating the catalyst by contacting said catalyst with an oxygen containing gas at a temperature from about 300° C. to 550° C., (b) impregnating the regenerated carbon-reduced catalyst with an impregnation solution which comprises a mixture of water and a combination of MoO3 and H3PO4, (c) aging the impregnated catalyst and (d) drying the aged catalyst. The invention also refers to the rejuvenated catalyst obtained and its use for hydrotreating hydrocarbon feedstocks.