Three long chain fatty acid substituted aminoanthraquinone (AAQ) were synthesized in the laboratory and evaluated as corrosion inhibitors for steel (API5L-X60) in diesel-water mixtures at room temperature by weight loss and electrochemical studies. Potentiodynamic polarization studies carried out at room temperature on steel (API5L-X60) in diesel with water containing 120 ppm of chloride and 50 ppm of aminoanthraquinone (AAQ) derivative showed that all the investigated compounds are of anodic type. The results obtained indicate that 1-aminoanthraquinone derivatives are good corrosion inhibitors in diesel-water mixtures. Oleic acid substituted aminoanthraquinone was found to be the best corrosion inhibitor. It exhibited 92% inhibition efficiency against the corrosion of API 5L-X60 steel in diesel-water mixtures. The surface analysis by AFM indicates the adsorption of synthesized inhibitors on the metal surface. (C) 2007 Elsevier Ltd. All rights reserved.