A study of the latch and breakdown phenomena in thin film SOI MOSFET's is performed as a function of temperature. The experimental analysis is concentrated on p-channel devices, for which no investigation of the parasitic bipolar transistor has been carried out. We show that latch problems are observed for thin-film p-channel devices in the sub-half-micrometer range. In addition, it is demonstrated by theoretical considerations and experimental results that these parasitic effects are strongly reduced at liquid nitrogen temperature, and vanish entirely at liquid helium temperature. Similar improvements are expected for low temperature operation of n-channel devices.