Department of Chemistry, D. A. V. College, Muzaffarnagar-251 001 (India) Manuscript received 17 December 1979, revised 30 July 1980, accepted 25 August 1980 The surface tension of strontium soaps in aqueous 2-propanol has been measured at 35�� and the data have been discussed on the basis of Langmluir's approximate equation : \(\gamma\)=\(\gamma\)0(1+X In Y)���X\(\gamma\)0 In C. Constants X and Y have been calculated for soap systems. Constant X is found to be independent of solvent composition in the mixture but it increases with increasing chain length of soaps. The values of Y show a marked change at 50% 2-propanol concentration which confirms that the change in nature of micelles takes place at about 50% 2-propanol concentration. The surface areas covered by 1 mol of the soaps have been evaluated