Physicochemical properties, such as foaming power, solubilizing power, suface tension and others, of a series of sodium N-alkyloyl sarcosinates (abbreviated as C_nCO sarcosinates) with n from 9 to 17 have been measured in relation to their alkyloyl chain length. These properties are highly dependent on the alkyloyl chain length as expected. The foaming power at 25°C increases at first with increasing chain length until n reaches to 15, and then decreases rapidly owing to the low solubility in water. The solubilizing power for an oil soluble dye, Yellow OB, increases with increasing chain length. The surface tension above the critical micelle concentration is approximately 35 dyne/cm irrespectively of the chain length. The solubility in water becomes low when n exceeds 15. The properties of the mixtures of C_nCO sarcosinates with different alkyloyl chain-length have been also examined. The effects of soap and water hardness on the foaming power of C₁₁CO sarcosinate were also reported.