Time‐dependent density measurements of the lowest xenon excited states (5p56s) in electron beam (e‐beam) pumped XeCl laser mixtures (nonlasing) are performed using pulsed hook interferometry. The e‐beam pulse length is ≊0.45 μs (full width at half‐maximum) with an average excitation rate of ≊250 kW/cm3. Density differences (ΔN∗) of transitions at 823.2 nm (6s[3/2]02 –6p[3/2]2), 828.0 nm (6s[3/2]01 –6p[1/2]0), and 840.9 nm (6s[3/2]02 –6p[3/2]1) are obtained for various HCl and Xe concentrations. For a 98.3% Ne/1.5% Xe/0.16% HCl mixture at 3000 Torr, ΔN∗ (823.2 nm) and ΔN∗(828.0 nm) are relatively constant at ≊3×1014 and ≊1.7×1014 cm−3, respectively. At lower initial HCl concentrations, the ΔN∗(823.2 nm) density starts out similar to the 0.16% HCl case, but tends to increase dramatically during the e‐beam pulse. For a 0.04% HCl mixture, a ΔN∗(840.9 nm) density of ≊4.5×1015 cm−3 is measured at the end of the e‐beam pulse. Preliminary comparisons of the data with a computer model show good agreement for HCl concentrations ≥0.16%, but disagreements at leaner concentrations.