A gas-phase surface sol-gel process was developed for facile preparation of ultrathin TiO2 gel/Cyt. c multilayered films. Positively charged Cyt. c protein was alternately assembled with TiO2 gel layer that was prepared by deposition of Ti(O-"BU)4 vapor and subsequent hydrolysis. The adsorbed Cyt. c molecule was covered with a 0.7-nm thick layer of TiO2 gel and the protein characteristics were preserved without denaturation in the multilayered film.