This paper presents an overview of emerging SOI technologies and their application to communication ICs. The unique properties of Si and SiO2, coupled with the broad range of achievable SiO2 film thicknesses, allow tuning of existing devices and the design of new devices targeting RF, high-speed wire line, and photonic communication applications. By using high-resistivity Si substrates, it becomes possible to realize inductors with Q as high as 50 as well as high-power RF switches. Record SOI NFET fT of 485GHz and fMAX of 430GHz have been measured, enabling the design of a broad range of high performance circuits, including 100GHz CML dividers, >100 GHz LC-VCOs, and 16Gb/s 8-port core back-plane transceivers. Finally, due to the large difference in refractive index between Si and SiO2, SOI technology allows the efficient design of photonic devices and circuits. © 2011 IEEE.