Abstract: A method is provided to remove metals from a residual oil containing an initial amount of a selected metal, the method comprising the steps of:providing a vessel for exposing the residual oil to a DC electric field having a strength of about one kV/inch or greater,passing the residual oils through the vessel whereby at least ten percent by weight of the initial amount of the selected metal is removed by attraction to an electrode; andpassing the residual oil that has been passed through the vessel over a hydrodemetalization catalyst in the presence of hydrogen. Metal containing particles and other toluene insoluble organic and inorganic solids are effectively removed from residual oil streams by treatment with a DC electrical field prior to hydrodemetalization resulting in significant increases in useful lives for downstream hydrodemetalization catalyst.