Abstract: A method is disclosed for the preparation of ceramic materials or articles by the pyrolysis of preceramic polysilanes wherein the preceramic polysilanes are rendered infusible prior to pyrolysis by exposure to ultraviolet irradiation in the presence of a reactive gas selected from the group consisting of ethylene, 1,3-butadiene, 2-methyl-1,3-butadiene, 1,4-pentadiene, silane, chlorosilane, dichlorosilane, boron trichloride, oxygen and water mixture, acetylene, and tetravinylsilane. This method is especially suited for the preparation of ceramic fibers. The ceramic fiber's surface properties can be modified by the practice of this invention; for example, a ceramic fiber with a carbon rich surface layer can be obtained when 1,3-butadiene is used as the reactive gas.