Hydrocarbonaceous feedstocks admixed with a flow-through catalyst and hydrogen are hydroprocessed in a hydroprocessing reactor containing a captive hydroprocessing catalyst. The flow-through catalyst is continually withdrawn with the hydroprocessed feed from the hydroprocessing reactor. The flow-through catalyst may be an FCC, hydrocracking, isomerization or ring-opening catalyst. In a preferred embodiment, the captive hydroprocessing catalyst contains Co, Ni and/or Mo on an alumina base and the flow-through catalyst is an FCC zeolitic catalyst which is withdrawn with the hydroprocessed feed from the hydroprocessing reactor and then sent to an FCC unit.