The flow properties of anhydrous sodium stearate have been followed in some detail over the temperature range 45° to 140 °C., using an extrusion plastometer. Comparative results have been obtained at a single temperature with the sodium soaps of some of the lower fatty acids. The results indicate large changes in the properties of sodium stearate at 68° and 105 °C. An abrupt change is also observed when the number of carbon atoms in the soap is reduced below eight.