The density and viscosity measurements of magnesium laurate in the mixture of chloroform -propyl-ene glycol at various temperatureshave been carried out in order to determine critical micellarconcentration, soap-solvent interactions and to study the nature of the micelles. The density and viscosity results were interpretedin terms of the equation proposed by Root, Einstein, Vands,Moulik and Jones-Dole.These results indicate the CMC values increase with increasing temperature and there is a significant interaction between soap and solvent mole-cules.