A mathematical model for reactive sputtering with multiple gases is established. Several non-dimensional parameters were identified with their physical significance and then the governing equations were cast in a non-dimensional form. For an illustration, a two-reactive gas system is used for study. Results show that the stability is characterized by the well-known hysteresis loop in the steady state solutions. Through parameter analysis, we found when the ion fluxes intensified, the range of hysteresis loops were enlarged and shifted to higher inflow rates. Moreover, when the chemical reactions dominate either on target or substrate, the steady state can be totally stable without hysteresis. Pumping speed also controls the process stability. At high pumping speed, excessive reactive gas is less likely to present in the chamber, leading to the extinction of hysteresis loops. (c) 2005 Elsevier B.V. All rights reserved.