Using a laser monitoring technique, the solubilities of 1,1'-(butane-1,4-diyl)-bis(pyridinium) dihexafluorophosphate in acetone (1) + water (2) have been determined experimentally from (278.15 to 328.15) K at atmospheric pressure. The experimental data were correlated with the modified Apelblat equation and the lambda h model. The calculated results showed good agreement with the experimental data. The solubility of 1,1'-(butane-1,4-diyl)-bis(pyridinium) dihexafluorophosphate in acetone + water is higher than that in water and acetone, respectively, and reaches the maximum value when the mass fraction w(2) = 0.30.