Science, Tech, Math › Science Substitution Reaction Definition What Is a Substitution Reaction in Chemistry? Share Flipboard Email Print Witthaya Prasongsin / 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 July 03, 2019 A substitution reaction is a type of chemical reaction where an atom or functional group of a molecule is replaced by another atom or functional group. A substitution reaction is also called a single displacement reaction, single replacement reaction, or single substitution reaction. Examples: CH3Cl reacted with a hydroxy ion (OH-) will produce CH3OH and chlorine. This substitution reaction replaces the chlorine atom on the original molecule with the hydroxy ion. Sources Imyanitov, Naum S. (1993). "Is This Reaction a Substitution, Oxidation-Reduction, or Transfer?". J. Chem. Educ. 70 (1): 14–16. doi:10.1021/ed070p14March, Jerry (1985). Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (3rd ed.). New York: Wiley. ISBN 0-471-85472-7.