Nanometer-scale oxide patterns were fabricated on Ti films deposited on Si(100) surface by means of atomic force microscope tip-induced anodization. The application of a negative bias voltage to a heavily doped silicon tip relative to the sample substrate permitted nanoscale lines and dots of titanium oxide to be formed directly on the titanium surfaces. Their sizes were dependent on the relative humidity, the scanning rate of the tip, and the pulse duration time. The spatial resolution of titanium oxide patterns was improved by increasing the tip scan rate and also by lowering the relative humidity. The smallest linewidth obtained in this experiment was about 18 nm. With increasing pulse duration time, the growth rate of oxide rapidly decreased. This result can be attributed to the decrease of the transport rate of ionic species through the existing oxide layer due to a reduction of electric field strength with increasing the oxide thickness.