The densities, kinematic viscosities, and specific conductances of mixtures of benzene with the Lewis acidic room-temperature chloroaluminate molten salt aluminum chloride + 1-methyl-3-ethylimidazolium chloride (AlCl3 + MeEtimCl) were determined at 298.2 K. Benzene was added to melts containing 51.00, 60.00, and 66.67 mol % AlCl3. Simple polynomial equations were fitted to the experimental results as a function of the mass fraction of benzene. The addition of small amounts of benzene resulted in a decrease in the kinematic viscosity and an increase in the specific conductance of the mixture. However, the addition of benzene beyond 35 mass % caused the specific conductance to decrease due to a decrease in the concentration of charge-carrying ions.