An esterified cellulose ether is provided wherein the ester groups are phthalyl groups, the degree of substitution of phthalyl groups is from 0.02 to 0.18, the degree of neutralization of phthalyl groups is not more than 0.75, and the esterified cellulose ether has a solubility in water of at least 2.0 weight percent at 2?C.