When studying the radiative emission of material, the sample surface temperature provides essential data for the interpretation of emission spectra. Surface temperature measurement, however, often remains a complex metrological problem. Difficulties are increased when the surface temperature of semi-transparent scattering media at high temperature ­ between 1000 K and 2500 K ­ is required. In this work, the technique of pyrometry at the Christiansen frequency was used to determine the surface temperature of ceramics. The objective of the study was to quantify the accuracy of this measurement technique. The uncertainty of temperature was calculated. However, given the difficulty of this estimation, a reliability indicator was also determined, defined as the maximum discrepancy between temperatures measured by two different techniques, namely pyrometry at the Christiansen frequency and infrared thermography. Comparison of temperature measurements are presented for a sintered sample of yttria stabilized zirconia. Corresponding emission spectra are described.