Science, Tech, Math › Science Disproportionation Definition in Chemistry It's a chemical reaction that produces two or more dissimilar products Share Flipboard Email Print AzmanL / Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated October 03, 2019 Disproportionation is a chemical reaction, typically a redox reaction, where a molecule is transformed into two or more dissimilar products. In a redox reaction, the species is simultaneously oxidized and reduced to form at least two different products. Disproportionation reactions follow the form: 2A → A' + A" where A, A', and A" are all different chemical species.The reverse reaction of disproportionation is called comproportionation. Examples Hydrogen peroxide converting into water and oxygen is a disproportionation reaction. 2 H2O2 → H2O + O2 Water dissociating into H3O+ and OH- is an example of a disproportionation reaction that is not a redox reaction.