The viscosities of some mineral salt viz.; potassium chloride, potassium nitrate, magnesium chloride, magnesium nitrate, at different concentrations have been determined in water and in binary aqueous solution of sodiumdodecyl sulfate (SDS) (0.007 mol . kg(-1) and 0.01 mol . kg(-1)) at different temperatures. The data have been analyzed using Jones-Dole equation and the derivative parameters B and A have been interpreted in terms of ion-solvent and ion-ion interactions respectively. The change of Gibbs free energy of activation (Delta G'(eta)), enthalpy of activation (Delta H(eta)(not equal)), and entropy of activation (Delta S(eta)(not equal)) for viscous flow of the solutions were calculated using Eyring equation, which depicts the mechanism of viscous flow. The structure making/breaking nature of the studied electrolytes has been discussed in the light of first derivative of B-coefficient (dB/dT) over temperatures. Potassium chloride and potassium nitrate acts as structure breaker in water where as all the salts are structure makers in aqueous SDS solutions, i.e. the postmicellar and pre-micellar regions. (C) 2011 Elsevier Ltd. All rights reserved.