Anhydrous Nylon 6-10, xH(3)PO(4) films have been studied by infrared and impedance spectroscopies. The CONH/acid interactions evolve from strong hydrogen bonding to protonation depending on acid concentration and temperature. Protonic conductivity reaches a value as high as 10(-3) S/cm at 25 degrees C for Nylon 6-10, 2.5 H3PO4.