The nonlinear current-voltage and dielectric properties of (Al3+ + Ta5+) co-doped TiO2 (ATTO) ceramics are represented. Microstructural analysis reveals that sintered ceramics are highly dense and nonporous. ATTO ceramics exhibit low loss tangent (tan delta < 0.1) and large dielectric permittivity (epsilon(similar to)10(3)-10(4)). Furthermore, ATTO ceramics exhibited nonlinear current-voltage characteristics. The best dielectric properties are achieved in the (Al1/2Ta1/2)(0.05)Ti0.95O2 ceramic with a very low tan delta ((similar to)0.012) and high epsilon' ((similar to)10(4)) with excellent dielectric-temperature stability with a temperature coefficient at 150 degrees C as low as 2.69%. The resistivity of insulating phases decreases with increasing Al3+ and Ta5+ concentrations, which is correlated to decreased breakdown voltage. The nonlinear electrical properties and dielectric response are explained based on the electrical response of internal interfaces.