A new composite material was fabricated by heat pressing a powder mix containing a sulfonated poly[(hydroxy)propyl, phenyl]ether (SPHPE), with empirical formula [-O-Ar-C(Me)(2)-Ar(SO3H)(0.4)-O-CH2CH(OH)-CH2-(center dot)1.5 H2O](n), and poly(dipropyl)phosphazene (PDPrP) to yield a film which was soaked in 85% H3PO4 (PA) and dried. The final SPHPE-PDPrP-PA film (0.15 cm thick) contained -SO3H functional groups and H3PO4 at 0.16 SO3H/N and 1.72 H3P04/N mole ratios. For the phosphazene polymer, at least two types of repeating units were present, i.e., -P(CH2CH2CH3)(2)=N- and -P(CH2CH2CH3)(2)=NH+(H2PO4-center dotH3PO4)- at 0.18 N/NH+ mole ratio. This material exhibited proton conductivity (sigma, Omega(-1) cm(-1)) of 2.27 10(-4) -7.10 10(-3) at 24 - 127 degrees C in dry environment, and of 4.79 10(-4)-1.54 10(-3) at 45-65 degrees C and 11% relative humidity. The results for SPHPE-PDPrP-PA composite are discussed by comparison to available literature data for other composites and polymers containing N protonated by H3PO4. (c) 2005 Elsevier B.V. All rights reserved.