The fluidity, Phi, of molten salts is re-examined with critically compiled data applicable to 75 salts of various charge types. Various theoretical approaches, based on the corresponding states principle applicable to molten salts, are briefly presented. They are compared with the much simpler approach of Hildebrand and Lamoreaux: Phi = -B+ (B/V-0)V that relates the (temperature dependent) fluidity to the (temperature dependent) molar volume V of the molten salt. This approach yields at the corresponding temperature of 1.1 T-m the B parameters that are linearly related to the cohesive energy and the V-0 parameters that are 87% of the molar volume, signifying the absence of free volume. (C) 2014 Elsevier B.V. All rights reserved.