In the design of rf sputtering systems, the electrical equivalent of the gas discharge must be known. For this purpose, an experiment was conducted in which the electrical impedance (capacitance and conductance) of an rf sputtering gas discharge was determined as a function of pressure, magnetic field strength, and rf power input. The method of measurement involved the use of a matching network, an incident and reflected power meter, and a Boonton radio-frequency admittance meter. Values of conductance and capacitance for the discharge were deduced from measurements on the matching network after termination of the discharge. Results show that both capacitance and conductance increase strongly with increasing magnetic field. Capacitance changed from 0.97×10−13 F/cm2 to 2.5×10−13 F/cm2 between zero and 156 G. Conductance changed from 1.6×10−6 mho/cm2 to 3.9×10−6 mho/cm2 in the same interval. Pressure dependence was strongest at zero magnetic field, changing both capacitance and conductance approximately 30% between 7.5 and 30 mTorr (argon). At high magnetic field, there was very little effect. No appreciable change was observed between 1.1 and 6.5 W/cm2 power application. Design equations are given for a simple matching network, and a design example is presented to demonstrate application.