2,6-Diamino-pyridinium dihydrogen phosphate.

In the crystal structure of the title compound, C(5)H(8)N(3) (+)·H(2)PO(4) (-), N-H⋯O hydrogen bonds, involving the unprotonated amino-group and the NH(+) group in the pyridinium ring and dihydrogenphosphate O atoms, link the cations and anions. A long chain-like stacking of dihydrogenphosphate anions along the c-axis direction is constructed by O-H⋯O hydrogen bonds. Also along the c-axis direction, π-π stacking between inversion-related pyridinium rings [centroid-centroid distance = 3.8051†(10)†à ] forms columnar stacks of cations.