AbstractAttempts were made for a critical examination of the use of ΔS°t as a structural probe to study the ion induced perturbations on aquo-alcoholic solvent mixtures. The division of the thermodynamic properties of TATB (tetraphenyl arsonium tetraphenyl borate) in solution into equal parts is not free from defects. Naturally, the calculation of single ion values based on TATB is also problematic. Dissection of the single ion values like TΔS°t(ion) as suggested by Kundu is full of errors. Analysis shows TΔS°t(ion) to be an insensitive parameter to determine the structural characteristics of aquo-alcoholic mixtures. Structure of aquo-alcoholic mixtures should be determined from the excess thermodynamic properties of mixing, excess dielectric properties of mixing, excess polarizabilities, the correlation parameter “g” etc. Other properties like ultrasonic sound absorption, excess volume and viscosity of mixing were found to be useful. Ion induced perturbations of any solvent system will be dictated by the structure of the particular solvent system. A knowledge of the structure of the aquo-alcoholic mixtures is imperative to develop an idea regarding ion induced perturbations as mirror image relations because of compensation of ΔH° and TΔS° (and of ΔH°t and TΔS°t) will be observed in any solvent system. The thermodynamic measurements provide a summary of all interaction energies over a long time. To comprehend the rational structural details of the solvent systems, accurate thermodynamic measurements alongwith relaxation experiments providing high time and good structural resolutions are necessary.