Na0 5K0 5NbO3 (NKN) and 10 mol% (Na K) excess Na0 5K0 5NbO3 (NKN10) thin films on Pt/Ti/SiO2/Si substrate were prepared by chemical solution deposition Crystallization of NKN10 thin films was confirmed by X-ray diffraction The (Na K) excess Na0 5K0 5NbO3 thin film shows a ferroelectric P-E hysteresis loop Dielectric properties and impedance spectroscopy of thin films were investigated in the frequency range from 0 1 Hz to 100 kHz and the temperature range of 25 similar to 500 degrees C By analyzing the complex impedance relaxation with Cole-Cole plots we found impedance relaxations for the thin film The contribution of electrical conduction is discussed in relation to grain grain boundary and Interface effects (C) 2010 Elsevier B V All rights reserved