The leakage drain current carriers (electrons and holes) of accumulation-mode (AM) p-channel silicon-on-insulator (SOI) MOSFETs and enhancement-mode (EM) n-channel SOI MOSFETs operating from room to high-temperatures up to 300 degreesC is discussed in this paper. The channel length L influences on the total leakage drain current I-Dleak Of both SOI MOSFETs types is also studied. It was observed that for transistors where the channel length are loa er than 20 mum, the total leakage drain current that Bows through the silicon film in the SOI pMOSFETs is composed mainly by holes and in the SOI nMOSFETs by electrons, operating up to 300 degreesC. Otherwise, when the channel length is higher than 20 mum, the leakage drain current is composed mainly by electrons for the AM SOI pMOSFETs and holes for the EM SOI nMOSFETs. Experimental data and numerical two-dimensional simulations were used to aim all results.