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(SO 3 H) 0.4 –O–CH 2 CH(OH)–CH 2 –•1.5 H 2 O] n , and poly(dipropyl)phosphazene (PDPrP) to yield a film which was soaked in 85% H 3 PO 4 (PA) and dried. The final SPHPE–PDPrP–PA film (0.15 cm thick) contained –SO 3 H functional groups and H 3 PO 4 at 0.16 SO 3 H/N and 1.72 H 3 PO 4 /N mole ratios. For the phosphazene polymer, at least two types of repeating units were present, i.e., –P(CH 2 CH 2 CH 3 ) 2 =N– and –P(CH 2 CH 2 CH 3 ) 2 =NH + (H 2 PO 4 − •H 3 PO 4 )– at 0.18 N/NH + mole ratio. This material exhibited proton conductivity (σ,Ω −1 cm −1 ) of 2.27 10 −4 –7.10 10 −3 at 24–127 °C in dry environment, and of 4.79 10 −4 –1.54 10 −3 at 45–65 °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 H 3 PO 4 .