Bis(4-acetoxy- N -ethyl- N - n -propyl-tryptammonium) fumarate-fumaric acid (1/1).

The solid-state structure of the title salt/adduct (systemic name: bis-{[2-(4-acet-yloxy-1 H -indol-3-yl)eth-yl](eth-yl)propyl-aza-nium} but-2-enedioate-( E )-butenedioic acid (1/1)), 2C 17 H 25 N 2 O 2 + ·C 4 H 2 O 4 2- ·C 4 H 4 O 4 , was determined by single-crystal X-ray diffraction. The asymmetric unit consists of a singly protonated tryptammonium cation, one half of a fumarate dianion and one half of a fumaric acid mol-ecule. In the crystal, the ions and mol-ecules are linked together in infinite chains propagating along [001] through a series of N-H⋯O and O-H⋯O hydrogen bonds.