1,1':4',1''-Terphenyl-2',5'-dicarb-oxy-lic acid dimethyl sulfoxide-d(6) disolvate.

The asymmetric unit of the title solvate, C(20)H(14)O(4)·2C(2)D(6)OS, contains half of the substituted terephthalic acid mol-ecule and one solvent mol-ecule. The centroid of the central benzene ring in the acid mol-ecule is coincident with a crystallographic inversion center. Neither the carboxyl nor the phenyl substituents are coplanar with the central aromatic ring, showing dihedral angles of 53.18 (11) and 47.83 (11)°, respectively. The dimethyl sulfoxide solvent mol-ecules are hydrogen bonded to the carb-oxy-lic acid groups.