The compact circuit simulation model HiSIM-SOI for silicon-on-insulator (SOI)-MOSFET solves the three surface potentials of the SOI-MOSFET accurately without sacrificing simulation time. Depending on device structure and biasing conditions the SOI-MOSFET device may operate in partially depleted (PD) or fully depleted (FD) modes and a smooth transition between these modes is prerequisite for a good compact model. HiSIM-SOI is verified to fulfill these requirements and to cover all the operational regions of SOI-MOSFETs. It is also demonstrated that the floating-body effect, which determines key SOI-MOSFET properties like the kink effect or the history effect, can be accurately captured within the model calculation in a simple way without introducing an additional node in the compact model. Furthermore, HiSIM-SOI correctly reproduces measured data of both body-contact and floating-body devices.