The two-step preparation of bis-4-(4-cyanatophenoxy)phenyl sulphone, in good yield and high purity, is reported. Characterization of the monomer is undertaken using spectroscopic and chromatographic methods and elemental analysis. Blends of bis-4-(4-cyanatophenoxy)phenyl sulphone with a commercial dicyanate, 2,2-bis(4-cyanatophenyl)propane are analyzed using differential scanning calorimetry at a variety of heating rates and the thermal data compared with those of the discrete monomers. The cured homopolymers and blends are further analyzed using thermogravimetry, dynamic mechanical thermal analysis and thermomechanical analysis. The effects of blend composition on the thermal stability, glass transition temperature and thermal expansion are discussed.