A slurry hydroconversion process is provided in which a carbonaceous chargestock such as a hydrocarbonaceous oil or coal comprising a catalyst containing vanadium or molybdenum or mixtures thereof, is converted to a hydroconverted oil product. A heavy oil portion comprising metal-containing solids is separated from the oil product and partially gasified to produce a carbon-free metal-containing ash which is extracted with oxalic acid. The resulting metal-containing oxalic acid extract is recycled to the hydroconversion zone as catalyst precursor.