The methyl substituted imidazole ring in the title compound, -methyl-4
-oxo-2,3,4,9-tetrahydro-1H-carbazol-3-yl) imidazol-3-ium chloride dihy
drate, C18H20N3O+.Cl-.2H(2)O, is approximately perpendicular to the ca
rbazole plane [dihedral angle 87.0(1)degrees]. The water molecules are
involved in an elaborate network of hydrogen bonds that reinforce the
stability of the dihydrate and the cohesion of the structure.