The effects of the pumping speed and the Ar/O-2 flow rate ratio on the transient time needed to reach a steady-state, after glow discharge ignition in Ti-O-2 reactive sputtering, were investigated. It was shown that the O-2 partial pressure, deposition rate, discharge voltage and the Ti emission intensity change continuously after glow discharge ignition until the process reaches a steady-state. The transient time increases as the pumping speed increases or as the Ar/O-2 ratio increases. The results suggest that a low pumping speed or a low Ar/O-2 ratio shortens the transient time for process operation parameter changes such as a reactive gas flow rate change.