a process for producing a mixed cellulose ether comprising reacting a starting cellulose ether with an etherifying agent is disclosed , wherein said starting cellulose ether comprises at least 18 mol % of a 6 - substituted glucose unit and at least 15 mol % of an unsubstituted glucose unit . a high utilization of the etherfifying agent can be reached . the resulting mixed cellulose ether has a high solubility in water and an aqueous solution of the resulting mixed cellulose ether has excellent properties such as flow properties and clarity .