The effects of annealing ambient (Ar, N-2, O-2 and N2O) and durations (60 and 200 s) of rapid thermal annealing (RTA) on the insulating property of RF sputtered tantalum pentoxide films were examined. It was found that films sputtered at 200 W were more leaky than those sputtered at 100 W. It was also discovered that RTA in O-2 and N2O and at a longer duration (200 s) improved the insulating property of the films. This improvement was suggested to be due to a layer of SiO2 formed at the Si-Ta2O5 interface when annealed. The conduction mechanism for the O-2 and N2O annealed films was found to be of Poole-Frenkel type.