The title compound, bis(oxotremorine) fumarate bis(fumaric acid) {systematic name: 1-[4-(2-oxopyrrolidin-1-yl)but-2-ynyl]pyrrolidinium (2E)-but-2-enedioate bis[(2E)-but-2-enedioic acid]}, 2C12H19N2O+·C4H2O42−·2C4H4O4, has a single oxotremorine monocation protonated at the pyrrolidine nitrogen, one fumaric acid molecule and half of a fumarate dianion in the asymmetric unit. The ions and fumaric acid molecules are held together by N—H...O and O–H-...O hydrogen bonds in 40-membered rings with graph-set notation R66(40). The fumarate ions join these rings into infinite chains along [001].
