Poly(4-hydroxystyrene) block copolymers containing maleic acid groups in one block were prepared through nitroxide mediated polymerization and their thin films with or without BaTiO3 nanoparticles were evaluated as a solution-processable dielectric materials. Poly(4-hydroxystyrene-co-maleic acid)-block-poly(4-hydroxystyrene) was successfully prepared through the hydrolysis of poly(4-acetoxystyrene-co-maleic anhydride)-block-poly(4-acetoxystyrene), as evidenced by GC, GPC, FT-IR and NMR. Through the incorporation of maleic acid group and BaTiO3 nanoparticles to poly(4-hydroxystyrene), higher dielectric constant was observed, suggesting that the dielectric constants of the composite films were strongly affected by the structural and compositional characteristics of polymers and nanocomposites.