Illumination of titanium thin films with an argon-ion laser has been used to fabricate nanometer scale features by localized oxidation. The laser induces a temperature gradient in the metal film, within which oxidation may occur. Due to the non-linearity of the reaction with temperature, the reaction zone can be laterally confined to regions narrower than the diffraction limit of optical resolution. Scanning probe microscopy indicates widths ranging from 105 to 600 nm and heights of 0.8 to 30 nm. The possibility of forming novel structures is demonstrated.