An overall evaluation of the transient thermo-reflectance (TTR) technique as applied to the measurement of thermal properties of electronic materials is presented in this article. First, the TTR method is presented. Then, the focus is placed on a systematic characterization of the performance of the thermoreflectance technique in which the influences of the most important system parameters on the accuracy of the TTR measurements are ascertained (Burzo et al., 2002). Finally, the power of the TTR measurement technique and its optimization are demonstrated through representative measurements, first of bulk materials (Komarov et al., 2003) and then of thin-film materials. Results are then shown addressing the effects of doping, isotopic purity, interface resistance, deposition/growing methods, and film thickness on the thermal properties of the selected bulk and thin-film layers