A method to extend the life of a residue hydrodesulfurization (HDS) catalyst during use was devised by injecting oil-soluble metal precursors to the feed oil intermittently. The method is based on the idea that oil-soluble metal precursors are transformed to catalytically active particles and that conventional HDS catalysts capture most of them. The resulting catalyst possesses additional HDS activity. The scheme was experimentally verified with the commercial vacuum residue HDS catalyst and an atmospheric residual oil that contained 310 ppm of molybdenum naphthenate and 60 ppm of cobalt naphthenate. The catalyst, which was exposed to the metal-containing oil, captured most of the dispersed particles and its HDS activity was improved. The improved catalytic activity requires a less-severe temperature increase policy, which will extend the life of the catalyst further. A less-expensive molybdenum-containing organic compound, MOLYVAN L, was as effective as molybdenum naphthenate in improving HDS activity when used with cobalt naphthenate. The conversion improvement of the bigger molecule, asphaltene, by the catalyst that was exposed to dispersed catalysts suggests that the deposited metals were located primarily on the outer surface of the catalyst.