The invention relates to a process for treating naphthenic acid--containing whole crudes or fractions thereof to reduce or eliminate their acidity by contacting the acidic whole crude or fraction at a temperature of from about 50.degree. C. to 350.degree. C. with a neutralizing amount of tetraalkylammonium hydroxide, preferably tetramethyl-ammonium hydroxide. The process has the additional benefits of reducing materials handling problems associated with treating oils using liquid solvents and in reducing emulsion formation.