The contact mechanical properties of the ZrB(2)-30% SiC ultra-high-temperature ceramic (UHTC) were studied from room temperature up to 800 degrees C in air, by combining Hertzian indentation tests with finite element modeling. It was found that the elastic modulus and yield stress decrease with increasing temperature, especially above 600 degrees C. It was also found that the ZrB2-30% SiC UHTC is "ductile" in the sense that its first damage mode is quasiplasticity, followed by cone cracking, and eventually by radial cracking. However, its contact-damage resistance degrades as the temperature increases, again especially above 600 degrees C. Nevertheless, it is highly damage tolerant because the critical loads for radial cracking are one order of magnitude greater than these for quasiplasticity. This is the first report on the temperature dependence of the Hertzian indentation of UHTCs, whose study is necessary if they are to be used in aerospace applications.