The solution density, viscosity and conductivity of MClO4 (M = Li and Na) solutions in propylene carbonate and gamma-butyrolactone are measured at the concentrations of < 1.5-2.0 mol dm(-3). The partial volume of the solute, derived from the density, of NaClO4 is greater than that of LiClO4 as expected. NaClO4 produces less viscous and more conductive solutions than LiClO4 throughout the examined concentration range. Notably, the conductivity of the NaClO4 solutions is 10-20% higher than that of the LiClO4 solutions at T/K = 298. The validity of the empirical cubic root law, Lambda(C) = Lambda(0) - AC(1/3), is examined, where Lambda and Lambda(0) are the molar conductivities at the molarity C and at infinite dilution. The meaning of the slope A is interpreted in the theoretical framework of the pseudolattice model. (C) 2012 Elsevier B.V. All rights reserved.