The objective of this work was to examine linear thermal expansion of K0.5Na0.5NbO3 ceramics between room temperature and 790 degrees C by contact dilatometry. The material was single phase with 95.5% relative density and with a uniform microstructure. Three distinct regions of thermal expansion could be discerned, corresponding to the three phases of K0.5Na0.5NbO3: monoclinic (assuming a single perovskite unit cell), tetragonal, and cubic, separated by discontinuities as typical for the first-order phase transitions. The linear coefficient of thermal expansion between 30 degrees and 195 degrees C is 2.96 x 10(-6) K-1, between 208 degrees and 364 degrees C is 4.35 x 10(-6) K-1, and between 434 degrees and 790 degrees C is 7.52 x 10(-6) K-1.