Tobermorite fibers have been successfully synthesized by hydrothermal reaction at 200degreesC under the pressure of 2 MPa after 3-10 h using a Ca(II)-EDTA complex precursor. XRD patterns, TG-DTA analysis, and SEM observations show that the products are needle-like tobermorite fibers, which have diameter, length, and aspect ratio in the range of 0.1-10, 40-100, and 20-80 mum, respectively. The fibers can maintain their shapes up to 1150 C during the heat treatment. (C) 2002 Elsevier Science Ltd. All rights reserved.