A water-soluble methyl cellulose ether, having a flocculation point below 100.degree. C., is manufactured by reacting methyl chloride and a cellulose activated by mercerizing the cellulose with aqueous alkali in the presence of a C.sub.2-C.sub.3 alkyl chloride as a reaction medium at a temperature from 65.degree. C. to 90.degree. C. and at a pressure from 3 to 15 bar. The weight ratio between the cellulose and the C.sub.2-C.sub.3 alkyl chloride is normally from 1:1 to 1:5. The use of the reaction medium makes it possible to produce at a low pressure methyl cellulose ether at a good rate.