1. An esterified cellulose ether which i) comprises groups of the formula —C(O)—R—COOH or a combination of aliphatic monovalent acyl groups and groups of the formula —C(O)—R—COOH, wherein R is a divalent hydrocarbon group, ii) has a weight average molecular weight Mw of up to 70,000 Dalton, iii) has a degree of neutralization of the groups —C(O)—R—COOH of not more than 0.4, and iv) has a solubility in water of at least 2.0 weight percent at 2° C., is useful for preparing enteric capsules.