The present invention relates to the use of a product obtainable by the reaction of a fatty acid, or mixture of acids, having the formula R1COOH (I); and a dicarboxylic acid or a derivative thereof having the formula (IIa) or (IIb) with an alkoxylated fatty amine having the formula (III) or a partial or wholly quaternized derivative thereof; optionally said reaction between the fatty acid, the dicarboxylic acid and the alkoxylated fatty amine is being followed by a further reaction step wherein part or all of the nitrogen atoms are quaternized by reaction with an alkylating agent R5X; as a corrosion inhibitor for metal surfaces. The present invention also relates to such products and to methods for their production.