A one-step, fast, and potential low cost process has been developed to fabricate silicalike glass nanostructures by combining sol-gel chemistry and thermal nanoimprint. An inorganic-organic sot-gel thin film is patterned at low pressure and temperature with flexible stamps. Various geometries are achieved with a patterning resolution of about 150 nm and pattern aspect ratio higher than 4. To obtain pure silica structures a thermal annealing at high temperatures is required. During this step most of the structures collapse due to fluidization of the sol-gel material. It is shown that if a suitable condensation level is obtained during imprinting, the nanostructures are thermally stable. (c) 2007 American Vacuum Society.