The aggregation of a calcium sulfonate in organic solvents was studied by the Fourier Transform Infrared (FTIR) spectroscopy and dynamic light scattering techniques. The symmetric stretching band of the S = O bond was found to be sensitive to the concentration of the additive and to the polarity of the solvent. A critical micelle concentration (CMC) may exist in the concentration range of 0.04–0.11 millimole/liter. As the solvent polarity increased, the width in half height of the symmetric stretching band of S = O increased, and the interaction between the solvent and the polar head of calcium sulfonate increased accordingly. This interaction weakened the interaction between the polar heads themselves, and thereby the size of the micelle decreased as found by dynamic light scattering. When the polarity of a solvent is strong enough, e.g., in heptanoic acid or water, the micelles formed may revert back to normal micelles. The FTIR spectra and aggregation size of calcium sulfonate in hexadecane showed that higher temperatures decreased the width in half height of the asymmetric stretching bands and concurrently decreased the size of the aggregation.Presented at the 50th Annual Meeting in Chicago, Illinois May 14–19, 1995