Itaconic acid, or methylenesuccinic acid, is an organic compound. Itaconic acid is a white crystalline powder. Itaconic acid is a naturally occurring compound, non-toxic, and readily biodegradable. The name itaconic was devised as an anagram of aconitic.

 Historically, itaconic acid was obtained by the distillation of citric acid. Since the 1960s, it is produced industrially by fermentation of carbohydrates such as glucose using Aspergillus terreus. As such, it is a fully sustainable industrial building block. It is primarily used as a co-monomer in the production of styrene-butadiene-acrylonitrile and acrylate latexes with applications in the paper and architectural coating industry.

 Since Cargill, the last of the U.S. companies to manufacture itaconic acid, exited the business, itaconic acid has mainly been procured by importing the product directly from China where it is still made by several different companies.