The dielectric properties of YCTO bulk capacitors were investigated as a function of temperature from 25°C to 150°C and at microwave frequencies in comparison to a SiO2 bulk sample. The results confirm the high-k character of the YCTO ceramic, in addition to the low AC conductivity, namely ε′ = 40.1 and σ = 6×10−8Scm−1 at 1MHz, and show a weak frequency and temperature (25°C–150°C) dependence. A temperature coefficient value of −601ppm°C−1 for the dielectric constant (TCε′) was estimated at 100kHz. In the GHz regime, a comparison with bulk SiO2 confirms the higher YCTO dielectric permittivity. These results demonstrate high-k YCTO ceramic as a very promising material with high potentiality for electronic applications.