A method for characterizing and optimizing refinery feedstock blends according to their corrosivity is provided. Refinery feedstocks can be characterized based on any of: dissociation of acids in the crude, breakup of naphthenic acid molecular associations, mass changes of carbon steel samples, and/or dissociation of sulfur compounds in the feedstocks. The characterization is performed as a function of temperature via any of electrical resistivity measurement, vibrational spectroscopic analysis, voltammetry, electrochemical impedance spectroscopy, crystal microbalance measurements of weight changes, and combinations thereof. The method employs models and/or hardware to optimize the usage of refinery feedstocks in the blending and valuation of the feedstocks.