1-(2-Hy-droxy-eth-yl)-4-{3-[(E)-2-(trifluoro-meth-yl)-9H-thioxanthen-9-yl-idene]prop-yl}piperazine-1,4-diium bis-(3-carb-oxy-prop-2-enoate).

In the title salt, C(23)H(27)F(3)N(2)OS(+)·2C(4)H(3)O(4) (-), a non-merohedral twin [ratio of the twin components = 0.402 (1):0.598 (1)], the -CF(3) group is disordered over two sets of sites with occupancy factors in the ratio 0.873 (2):0.127 (2). The dihedral angle between the two outer aromatic rings of the 9H-thioxanthene unit, whose thio-pyran ring has a screw-boat conformation, is 33.01 (9)°. The diprotonated piperazine ring adopts a chair conformation. In the crystal, inter-molecular O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds between neighboring mol-ecules form zigzag chains along the a axis and contribute to the stabilization of the packing.