4-Hy-droxy-N,N-diiso-propyl-tryptammonium hydro-fumarate.

The solid-state structure of the title salt, C(16)H(25)N(2)O(+)·C(4)H(3)O(4) (-) {systematic name: [2-(4-hy-droxy-1H-indol-3-yl)eth-yl]bis-(propan-2-yl)aza-nium (2E)-3-carb-oxy-prop-2-enoate}, is reported. In the extended structure, the hydro-fumarate anions form linear chains propagating in the [100] direction through O-H⋯O hydrogen bonds that combine with the tryptammonium cations to generate a three-dimensional network linked by O-H⋯O and N-H⋯O hydrogen bonds.