Oriented arrays of titania nanoribers have been fabricated by a simple and easily scalable method. Exposure to a 5 % H-2/95 % N-2 gas mixture at 700 degreesC transforms dense, polycrystalline rutile (TiO2) into arrays of single-crystal nanofibers (15-50 nm diameter; see Figure, scale bar: 1 mum). The arrays could be used in of environmental, biomedical, transportation, chemical processing, and sensing applications.