(Na0.8K0.2)0.5Bi0.5TiO3 thin films have been prepared on Pt/TiO2/SiO2/Si and p-type Si substrates using a metalorganic solution deposition method. The films annealed at 700 °C crystallize well and present perovskite phase. The films exhibit a well-defined hysteresis loop at an applied voltage of 4 V, with a remanent polarization of 4.7 μC/cm2 and a coercive field of 38 kV/cm. The films also show fatigue-free response up to 1.5×1010 switching cycles. The relaxor behavior of the films is confirmed by the frequency-dependence of capacitance-temperature relation. The capacitance-voltage curves show that the films are polarization-type switching and the memory window is about 2.5 V at ±4 V applied dc bias voltages. The changes of dielectric constant and dissipation factor with frequency are also investigated briefly.