In this study, electrical properties of Al2O3 deposited by Atomic Layer Deposition (ALCVD) on n-type 4H-SiC were investigated. Metal-Oxide-Semiconductor (MOS) capacitors were characterized by various electrical techniques such as Capacitance-Voltage (CV), Current- Voltage (IV) and Deep Level Transient Spectroscopy (DLTS) measurements. Two different oxidants, H2O and O3, have been used for the oxide deposition. After deposition, the flat-band voltage shift is much less using O3 than H2O (~ 7V versus ~ 20V). Annealing treatment has been carried out at different temperatures in Ar atmosphere up to 700°C. Whereas the flat-band voltage shift can be reduced by annealing, the leakage current remains rather high.