PURPOSE: To provide a method for producing a high-purity monoalkyl sulfate with industrial advantage according to a remarkably industrially simple method free from a problem about, e.g. formation of a sulfate as a by-product.

CONSTITUTION: This method for production of a high-purity monoalkyl sulfate is carried out by reacting a dialkyl sulfate with an alkaline agent in an aqueous solvent, condensing and/or drying the resultant reaction product if necessary, extracting excessive dialkyl sulfate with an organic solvent capable of dissolving it or miscible with it and removing it into the organic solvent layer. If concentration and/or drying is carried out under ordinary pressure or reduced pressure, a high-purity solid monoalkyl sulfate can be obtained. As the solvent for dissolving the dialkyl sulfate, a lower ketone, a lower alcohol or a Cellosolve is used. As the solvent miscible with the dialkyl sulfate, a ketone, a hydrocarbon or an organic acid ester is used. The above-mentioned reaction is conducted at 15 to 90°C by using 1mol dialkyl sulfate and 0.1 to 1.0mol alkaline agent.