Recently fabricated silicon-on-sapphire (SOS) wafers show improved electrical properties. This was demonstrated by both wafer and device-level characterization, in a wide range of temperatures (from 20 to 400 K). We discuss Hall effect measurements in bare SOS wafers as well as transistor properties in n- and p-channels (mobility, threshold voltage, subthreshold swing, and leakage currents). The short-channel effects are investigated in terms of charge sharing, drain-induced barrier lowering and fringing fields. Nonstatic measurements reveal a very long drain current overshoot at low temperature. Additional radio frequency measurements show excellent performance in the microwave domain.