High molecular weight phthalazinone containing poly(arylene ether)s, poly(arylene thioether)s, and poly(arylene sulfone)s with very high glass transition temperatures were synthesized from a series of new bisphthalazinone monomers. Bisphthalazinone monomers 7a-c and 8c were synthesized from 2-(4-chlorobenzoyl)benzoic acid in high yields. Poly(arylene ether)s and poly(arylene thioether)s were synthesized in NIT-dimethylacetamide (DMAc) in the presence of anhydrous K2CO3 by a nucleophilic substitution reaction between these bisphthalazinone monomers and activated difluoro compounds. The poly(arylene thioether)s were further oxidized to form poly(arylene sulfone)s, which would be very difficult, if not impossible, to synthesize by other method. All synthesized polymers have extremely high Ts and thermal stability as determined from DSC and TGA analysis. Poly(arylene sulfone)s have the highest T(g)s ranging from 288 to 333 degreesC. The poly(arylene ether)s and poly(arylene thioether)s described, having inherent viscosities in the range of 0.37-1.01 dL/g, are soluble in chlorinated solvents such as chloroform and could be cast into flexible films from solution. In contrast to their precursors, the poly(arylene sulfone)s described are not soluble in chloroform but are soluble in dipolar aprotic solvents such as DMAc.