Experimental results regarding the electrical characteristics of thin SiO2 films for use as gate insulators in metal-oxide-semiconductor (MOS) devices, grown by a newly developed catalytic water vapor generator (WVG) are presented. The advantages of this oxidation system include oxidation possibilities with excess oxygen or excess hydrogen. The MOS capacitor leakage current and the charge-to-breakdown (Q(BD)) characteristics of films grown with stoichiometric water vapor as well as films grown with water vapor containing excess oxygen or excess hydrogen are presented. These results demonstrate that superior Q(BD) values can be obtained by this system, with respect to those obtained by dry oxidation. Annealing experiments demonstrate that the Q(BD) values as well as the leakage current of SiO2 films grown with excess hydrogen can be improved using 10%O-2+90%Ar ambient. Pure Ar annealing is shown to give rise to notably improved gate voltage shift. The above results are explained by the aid of a model. Finally, (100) and (111), P-channel and N-channel MOS field effect transistors (MOS-FETs) were fabricated with gate oxides grown by the catalytic WVG. The I-V characteristics of these transistors are shown to be comparable to those of identical MOS-FETs but with gate oxides grown by conventional dry oxidation, indicating that this oxidation technique is compatible for device fabrication.