Critical micelle concentration is an important characteristic property of a surfactant and various methods such as osmotic pressure, surface tension, interfacial tension, UV-Visible spectrophotometry have been reported to determine it. The drop weight method was used to determine the Hadkar factor H 1 for organic liquid lighter than water and Hadkar factor H 2 was used for organic liquid heavier than water. The plot of H 1 or H 2 vs concentration of the aqueous surfactant solution was used to determine the critical micelle concentration of the surfactant. Interfacial tension between the aqueous surfactant solution and the organic liquid was also determined using Hadkar factors H 1 and H 2 .