Trace element levels of heavy metals in crude oil are reduced by contacting the crude oil with an oxidizing agent, converting heavy metals into heavy metal cations for subsequent separation from the crude oil. At least a complexing agent is added to convert the heavy metal cations into soluble heavy metal complexes in a water phase, which can be separated from the crude oil, for a treated crude oil having reduced levels of heavy metals. In one embodiment, the complexing agent is selected from the group of metal halides, and the oxidizing agent is selected from the group of organic peracids, inorganic peracids and salts thereof.