The temporal variation of the electron and current densities as well as the discharge voltage in a XeCl excimer laser discharge is studied as function of gas pressure and HCl+Xe concentration. The results show that independent of pressure and gas mix composition the electron drift velocity is a constant of vd=(1.2±0.2)×106 cm s−1. While in discharges containing only helium the current and electron density are independent of pressure P, both quantities vary as P0.6 once Xe and HCl have been added. The results are examined considering the most important atomic reaction rates.