Electrochemical methods were used in a systematic investigation of the abilities of the homologous straight chain mono- and α,ω-dicarboxylates to inhibit corrosion of mild steel, copper, and aluminum in aerated, mildly saline, and near-neutral aqueous solutions. Performance of both compound types was shown to be critically dependent upon their chain length, the metal, and the number of carboxylate groups. For dicarboxylates, with the possible exception of mild steel, longer chain lengths were found advantageous. This was not true for monocarboxylates, which showed abrupt decreases in inhibitor ability outside the optimal range. The dramatic variations in inhibitor efficiencies probably resulted from competing reactions, such as adsorption and complexation at the metal (hydr/oxide) surface, solubility, and micelle formation.