4-Hydr-oxy-2,2,6,6-tetra-methyl-piperidinium chloride-hydroxonium chloride (3/1).

The crystal structure of the title compound, C(9)H(20)NO(+)·Cl(-)·0.33(H(3)O(+)·Cl(-)), is composed of 4-hydr-oxy-2,2,6,6-tetra-methyl-piperidinium cations, hydroxonium cations and chloride anions, which are connected via O-H⋯O, O-H⋯Cl and N-H⋯Cl hydrogen bonding. The 4-hydr-oxy-2,2,6,6-tetra-methyl-piperidinium cation and one of the two crystallographically independent chloride anions are located on a mirror plane. The hydroxonium cation is located on a threefold axis and the second crystallographically independent chloride anion is located on a sixfold rotoinversion axis. Due to symmetry, the hydroxonium cation is disordered over two positions.