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.