Ti oxide films with varying stoichiometries and different crystal structures were prepared by reactive direct current magnetron sputtering in oxygen-depleted plasmas. The complex dielectric permittivity ε was determined in the 10-3-107 Hz range from measurements using a capacitor configuration. The real and imaginary parts of ε displayed power-law dependences from approximately 10 Hz up to a value between 1 and 10 kHz. Our data could be rationalized in terms of a model for screened hopping of vacancy-induced charge carriers, but the details remain poorly understood.