Maleic acid is an industrial raw material for the production of glyoxylic acid by ozonolysis. It is mainly used as a precursor to fumaric acid.

Maleic acid may be used to form acid addition salts with drugs to make them more stable, such as indacaterol maleate. It is used for making Maleate Salts of Bulk-Drugs like Pheneramine Maleate, Chloropheneramine Maleate and others. It is also used to prevent rancidity in oils. Maleic acid has become a new acidulant in food and beverage industry. It can enhance special fruit aroma and improve the taste in food and beverage. At the present time Maleic acid is mainly used in syrup, ready-tea, orange juice, sports beverage and other fortified syrup and food. In addition, Maleic acid is also used to manufacture unsaturated polyester resin, pesticide, tartaric acid, fumaric acid, succinic acid, DL-Malic acid, dyeing auxiliary and preservative grease.

It is commercially available as the crystalline material or as an aqueous solution in water (40%). It may contain fumaric acid (0.1%) and water (less than 0.5%) as impurities.