Aluminum pigments react in aqueous alkaline media (e.g., water-borne paints) by the evolution of hydrogen. Maleic acid copolymers, which were synthesized by copolymerization of maleic acid anhydride, styrene, and acrylic esters (ethyl-, n-butyl-, n-hexyl-, n-dodecyl-, and n-octadecyl acrylate) inhibit this corrosion reaction. With the increasing chain length of the ester alcohol of the acrylate monomer, the evolved hydrogen volume decreases (i.e., the corrosion inhibiting effect increases). There seems to be a potential correlation between the number of carbon atoms of the ester alcohol of the copolymers and the evolved hydrogen volumes. With the addition of 0.5 wt % of the copolymers with n-butyl, n-hexyl, n-dodecyl-, and n-octadecyl acrylate no hydrogen evolution was observed at pH 8 within 21. days (complete corrosion inhibition). Conductivity measurements of aqueous copolymer solutions indicate that with an increasing chain length of the ester alcohol, the copolymers possibly associate by hydrophobic bonding.