An anionic cellulose ether obtainable by a process comprising reacting an alkali metal cellulose with one or more reagents A selected from the group consisting of haloacetic acids, alkali metal haloacetates, alkali metal vinyl sulfonates, vinyl sulfonic acid, and precursors thereof, and one or more reagents B having the formula R.sup.1 --(OCH.sub.2 CH(R.sup.2)).sub.n -P, wherein R.sup.2 represents hydrogen or a methyl group; n is 0-2; P represents a glycidyl ether group, a 1,2-epoxy group or a precursor thereof, if P represents a glycidyl ether group, R.sup.1 represents a linear C.sub.3 -C.sub.5 alkyl group, optionally containing an oxygen atom, a phenyl group, or a benzyl group, and if P represents a 1,2-epoxy group, R.sup.1 represents a linear C.sub.3 -C.sub.5 alkyl group, optionally containing an oxygen atom. Preferably, reagent A is chloroacetic acid and reagent B is n-butyl glycidyl ether. The invention also relates to the use of said anionic cellulose ether as an associative thickener, rheology modifier or stabilizer.