The densities, kinematic viscosities, and specific conductances of mixtures of the organic cosolvents acetonitrile, benzene, and dichloromethane with the Lewis basic room-temperature chloroaluminate molten salt aluminum chloride + 1-methyl-3-ethylimidazolium chloride(AlCl3 + MeEtimCl) were determined at 25 degrees C. Cosolvents were added to melts containing 49.00 and 44.40 mol % (m/o) AlCl3. Polynomial equations were fitted to the results as a function of the mass fraction of the cosolvent. The addition of relatively small amounts of these cosolvents causes a significant decrease in viscosity and a large increase in the conductivity of basic melts.