Previous conflicting reports concerning fully-depleted SOI device hot electron reliability is partially due to misunderstanding over the maximum channel electric field (Em). Experimental results using SOI MOSFETs with body contacts indicate that Em is just a weak function of thin-film SOI thickness (Tsi) and Em can be significantly lower than in a bulk device with drain junction depth (Xj) comparable to Tsi. The theoretical correlation between SOI MOSFET's gate current and substrate current are experimentally confirmed. This provides a means (IG) of studying Em in SOI device without body contacts. Both N- and P-MOSFETs can have better hot-carrier reliability than comparable bulk devices. Thin film SOI MOSFETs have better prospects for meeting breakdown voltage and hot-electron reliability requirements than previously thought.