In the cation of the title compound, C10H13N2O(+)·I(-), all non-H atoms, with the exception of the O atom, are essentially coplanar, with a maximum deviation of 0.04 (1) Å. In the crystal, the cations and anions are arranged in layers parallel to (100). The cations are connected to the anions via an O-H⋯I hydrogen bond and there are significant π-π stacking inter-actions between cation layers, with centroid-centroid distances in the range 3.606 (5)-3.630 (5) Å. A weak intra-molecular C-H⋯O hydrogen bond is also observed. The crystal studied was an inversion twin with refined components of 0.52 (5) and 0.48 (5).