An esterified cellulose comprising aliphatic monovalent acyl groups and groups of the formula —C(O)—R—COOH, R being a divalent hydrocarbon group, has the following properties: i) the degree of neutralization of the groups —C(O)—R—COOH is not more than 0.4, ii) the total degree of ester substitution is from 0.03 to 0.38, and iii) the esterified cellulose ether has a solubility in water of at least 2.0 weight percent at 20° C.