Lead-free K0.48Na0.52NbO3 (KNN) ferroelectric thin films were prepared using the radio-frequency magnetron sputtering method. The crystallized KNN phase was confirmed using X-ray diffraction. The KNN thin film exhibited a well-saturated ferroelectric polarization-electric field hysteresis loop with high remanent polarization. The dielectric and electrical properties of the KNN thin film were investigated over a wide range of frequencies from 10 Hz to 1 MHz, and over a wide range of temperatures from 25 degrees C to 500 degrees C. The complex impedance relaxations are shown in an impedance Cole Cole plot. With increasing temperature, the AC conductivity increased, which obeys the power law, sigma(omega) = sigma(0) + A omega(5). The activation energy for the conduction process is calculated to be 0.57 eV from the slope of the AC conductivity at the low frequency. (C) 2010 Elsevier B.V. All rights reserved.