In the crystal structure of the title compound, C(14)H(12)NS(+)·CF(3)SO(3) (-), N-H⋯O hydrogen bonds link cations and anions into ion pairs. Inversely oriented ion pairs form stacks through multidirectional π-π inter-actions among the acridine units. The crystal structure features a network of C-H⋯O inter-actions among stacks and also long-range electrostatic inter-actions among ions. In the packing of the mol-ecules, the acridine units are nearly parallel in stacks or inclined at an angle of 33.07 (2)° in the four adjacent stacks with which they inter-act via weak C-H⋯O inter-actions. The methyl-sulfanyl group is twisted through an angle of 60.53 (2)° with respect to the acridine ring.