Mercury is removed from crude oils, natural gas condensates and other liquid hydrocarbons by first removing colloidal mercury and solids that contain adsorbed mercury and then treating the hydrocarbons with an organic or inorganic compound containing at least one sulfur atom reactive with mercury. The sulfur compound reacts with dissolved mercury that contaminates the hydrocarbons to form mercury-containing particulates that are then removed from the hydrocarbons to produce a purified product having a reduced mercury content. Preferably, the treating agent is an organic sulfur-containing compound such as a dithiocarbamate or sulfurized isobutylene.