In the title compound, Na+·C6H4Cl2NO2S−·1.5H2O, one of the water molecules lies on a twofold axis. There is no interaction between the N atom and the sodium ion. The sodium ion exhibits a pseudo-octahedral coordination defined by three water O atoms and three sulfonyl O atoms from three different anions. The S—N distance of 1.588 (2) Å is consistent with an S=N double bond. The crystal structure is stabilized by O—HN and O—HCl hydrogen bonds.