A material with low dielectric constant was produced using nanoparticle phosphotungstic acid (PWA) modified by the silane coupling agent -aminopropyltriethoxysilane (KH-550) dispersed in a poly(aryl ether ketone) containing (3-trifluoromethyl) phenyl side groups (FPEEK) matrix synthesized with (3-trifluoromethyl) phenyl hydroquinone (3FHQ) and 4,4-difluorobenzophenone. The material was fabricated using solution-blending. Moreover, the dielectric, thermal, and mechanical properties of this material were characterized using a precision impedance analyzer, thermal gravimetric analyzer, and universal tester, respectively. The results indicate that modified PWA (m-PWA)/FPEEK composites show obvious improvement in the dielectric properties compared to unmodified PWA (p-PWA)/FPEEK composites. This should be attributed to the good dispersion and compatibility of m-PWA in FPEEK, as proven by scanning electron microscope and wide-angle X-ray diffraction. Besides, m-PWA/FPEEK composites also exhibited the relatively good thermal and mechanical properties. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013