Itaconic acid, or methylidenesuccinicacid, is an organic compound. This dicarboxylic acid is a white solid that is soluble in water, ethanol, and acetone. Historically, itaconic acid was obtained by the distillation of citric acid, but currently it is produced by fermentation. The name itaconic acidwas devised as an anagram of aconitic acid, another derivative of citric acid.

Itaconic acid is primarily used as a co-monomer in the production of acrylonitrile butadiene styrene and acrylate latexes with applications in the paper and architectural coating industry.