25I-NBOMe (2C-I-NBOMe, Cimbi-5, also shortened to "25I") is a synthetic hallucinogen that is used in biochemistry research for mapping the brain's usage of the type 2A serotonin receptor; it is also sometimes used for recreational purposes. A derivative of the substituted phenethylamine 2C-I family, it is the most well-known member of the 25-NB family. It was discovered in 2003 by chemist Ralf Heim at the Free University of Berlin, who published his findings in his PhD dissertation. The compound was subsequently investigated by a team at Purdue University led by David Nichols.