(100) Si and 4 degrees off (100) Si were oxidized in dry oxygen, and the differences in thermal oxidation behaviour, oxidation-induced stacking faults and capacitance-voltage characteristics were investigated. The thickness of the oxide produced by oxidation of the silicon samples in dry oxygen in the temperature range 1000-1200 degrees C was measured using an ellipsometer. The oxidation rates of the 4 degrees off (100) Si were faster than those of the (100) Si but the differences between them decreased as the oxidation temperature increased. The size of the oxidation-induced stacking faults increased as the oxidation time and temperature increased from 1100 to 1200 degrees C. The density of oxidation-induced stacking faults was lower for the 4 degrees off (100) Si than for the (100) Si. Variations in the capacitance-voltage characteristics with the oxidation temperature showed that the flat band voltages were shifted positively. The fixed surface state charge density and the interface trapped charge density of the 4 degrees off (100) Si were lower than those of the (100) Si. Si lattice strains induced by excess interstitial Si atoms were investigated through convergent beam electron diffraction. The lattice strain of the 4 degrees off (100) Si was lower than that of the (100) Si and this showed that the 4 degrees off (100) Si had a lower interstitial concentration.