An experimental study was carried out on the use of a mixture of CO2 and Xe as the propellant for an electron bombardment ion thruster. The working performance parameters of the ion thruster under different flow mixing conditions were investigated using measurements and diagnostics such as power supply electrical parameter measurements, thrust measurements, and plasma diagnostics. In-depth studies of the particle species and the main electron collision reactions in the discharge chamber were carried out. The results showed that the CO2 in the discharge chamber led to a significant increase in the mean anode voltage and voltage oscillation amplitude, and the direct participation of CO2 in the discharge reaction could effectively improve the beam current and thrust of the ion thruster. When 5 sccm of CO2 was injected into the discharge chamber, the maximum measured thrust was increased by approximately 31.8 % compared to the state without CO2 injection. The addition of Xe led to a significant decrease in the discharge voltage and hence an increase in the electron number density, which significantly promoted CO2 dissociation and ionization. The insights obtained from this work can provide ideas for subsequent research related to an ion thruster using a mixed propellant. •A mixed working medium supply method for electron bombardment ion thrusters has been designed.•The ion thruster could start successfully and continuously operate stable under the mixed working medium supply method.•The significant gain of the CO2/Xe mixed working medium for the thrust of the ion thruster and its mechanism were verified.•The use of CO2 as a propellant can effectively improve in-situ resource utilization.•This work may provide more options for the propulsion systems of deep-space exploration missions.