A one-pot synthesis of polytitanosiloxanes (PTS) and its transformation to SiO2-TiO2 ceramic fibers were investigated. PTS was prepared by the hydrolysis of tetraethoxysilane followed by the reaction with bis(2,4-pentanedionato)titanium diisopropoxide in methanol in 33-95 SiO2 mol %. PTS was considered to be a ladder- or sheet-type polymer consisting of Si-O-Si and Si-O-Ti linkages as a main chain with pendant hydroxyl and 2,4-pentanedionato groups. SiO2-TiO2 ceramic fibers were prepared by the pyrolysis of SiO2-TiO2 precursor fibers, which were prepared by the dry spinning of PTS followed by steam treatment. The tensile strength was 610 MPa for the SiO2-TiO2 fibers (SiO2/TiO2 = 20) after the pyrolysis at 700 degrees C.