A novel procedure for the purification to surface chemical standard of sodium n-dodecyl sulfate and its retrieval as a solid is presented, As a result of their nature and relative surface activity with respect to the product, very small amounts of impurity can significantly alter the result of surface tension experiments. In addition to the preparation, the surface chemical behavior of the product is analyzed and compared with previously published data. Additional suggested criteria for purity are also applied, and their validity is discussed.