Department of Chemical Technology, University of Bombay, Bombay-400 019 Manuscript received 20 November 1981, accepted 28 April 1982 Pure sodium salts of odd and even chain fatty acids (C7 to C12) were prepared and their properties and performance characteristics were evaluated. The odd and even chain fatty acid soaps, in water, appear to behave as two separate surfactant series with respect to their solubility and critical micelle concen­tration ; the higher soaps behave somewhat anomalously perhaps due to coiling of longer hydrophobic chains in aqueous solutions, while the lower soaps having very high CMC are ineffective as surfactants at the usual concentrations.