3-Methyl-2-vinyl-pyridinium phosphate.

In the title salt, C8H10N(+)·H2PO4 (-), the cation is essentially planar (r.m.s. deviation = 0.063†à ). In the crystal, the phosphate anions form inversion R 2 (2)(8) dimers via pairs of O-H⋯O hydrogen bonds. These dimers are further linked by pairs of O-H⋯O hydrogen bonds, also enclosing R 2 (2)(8) loops, forming chains running along [001]. The cations are bonded to the anions via N-H⋯O hydrogen bonds and C-H⋯O contacts.