Reactive sputtering is a widely used technique to deposit oxides, nitrides, etc. A serious drawback of this technique, however, is the drastic decrease in deposition rate that almost always occurs when depositing compound films as compared to depositing pure metal film. In many cases it is possible to overcome this problem by operating the process in the narrow critical processing region between metallic and compound mode sputtering. In this processing region, however, the composition of the deposited compound thin film is extremely sensitive to the processing conditions. It is, therefore, very interesting to investigate the sensitivity of different processing parameters on the overall processing behavior. Computer modeling can be used as a tool to increase the understanding of this complex process. We will show that such results can be used to illustrate the individual effects of the major involved processing parameters. It also serves to assist in the work of process optimization. The relationship between target poisoning, argon current density, deposition rate, reactive gas supply, partial pressure, total pressure, and film composition have been carefully examined. In particular, we will point out a serious limitation that may arise during high rate multielement reactive sputter deposition. The effect of different reactivity of the involved elements may cause that one of the elements during deposition will not be fully oxidized.