Thanks to their structure, the SOI technologies present several intrinsic advantages for analog and RF applications. Indeed, as it is well established now, these technologies allow the reduction of the power consumption at a given operating frequency. Moreover, the high-insulating properties of SOI substrates, in particular when high resistivity substrate is used, make that these technologies are perfect candidates for mixed-signal applications. In the present paper, we will discuss the performances of the SOI technologies in radio-frequency range. First of all, the high-frequency behavior of SOI substrates, thanks to the characterization of transmission lines, will be shown. The impact of the SOI substrate resistivity on the performances of passive components will also be analyzed. Then, an overview of RF performances of SOI MOSFETs for two different architectures, fully- and partially-depleted, will be achieved and compared to the bulk ones. Finally, the influence of some specific parasitic effects, such as the kink effect, the self-heating effect and the kink-related excess noise, on the RF performances of SOI devices will be studied, thanks to a specific high-frequency characterization.