Ion conducting thin films of lithium-niobium-oxynitride were produced by r.f. sputtering from an LiNbO3 target in nitrogen-containing atmosphere, using an unbalanced-magnetron configuration. It is believed that incorporation of nitrogen into the film structure, enhanced by the unbalanced-magnetron deposition, lowered the activation energy from 0.7 to 0.35 eV. As a result, very good ionic conductivity of about 2.5 x 10(-5) S cm(-1) at room temperature was achieved.