Butylated hydroxytoluene (BHT), a lipophilic bio-active organic molecule and chemically, a phenol derivative added to many food materials to prevent fat spoilage and moreover, as additive to many pharmaceutical products. On the other hand, sodium dodecyl sulfate (SDS) has also been employed as major raw material by many industries. Taking into account the advantages of surfactant micelles as carriers, the impact of BHT on SOS micellar system has been studied in ethanol and in different percentage compositions of ethanol + water mixtures. Therefore, it would be interesting and of great value to evaluate the type of interactions occurring between BHT and SOS in order to design such system which could prove its validity in food or pharmaceutical formulations. In order to examine the micellar properties more clearly, we use simple and easily controlled approach to obtain critical micelle concentration (CMC) values using conductance (K) along with experimentally determined density and speed of sound data to evaluate, apparent molar volume (phi(nu)), apparent molar adiabatic compression (phi(kappa)) and isentropic compression (K-s) of SOS in presence of BHT at variable temperatures (25, 30, and 35 degrees C). Further, the thermo-acoustic parameters have also been evaluated using viscosity measurement. In addition, spectroscopic analysis (FTIR and proton NMR) confirmed the interaction between BHT and SOS and locus of BHT in micellar structure. Conclusively, this physicochemical study provides a hint to assess and develop surfactant immobilized BHT for better biological action. (C) 2014 Elsevier B.V. All rights reserved.