Pyrolytic carbon films were prepared by chemical vapor deposition on Si-Ti-C-O ceramic fiber, using argon or hydrogen as dilute gas with methane gas. The effects of argon or hydrogen gas on the deposition process were investigated in terms of the temperatures and the duration of the incubation period preceding the formation of the film. When argon was used as the dilute gas, carbon films were formed in the temperature range between 1350 K and 1550 K, but when hydrogen was used, there was no deposition at temperatures below 1450 K. The activation energy for carbon film formation was 110 kJ/mol. The duration of the incubation period was about 1 ks. The incubation time might have been delayed because residual hydrogen from the hydrogen-cleaning pretreatment hindered the film formation process and the surface conditions of the films had changed.