PURPOSE: To increase dispersibility of alkali to cellulose and product yield by premixing an alkaline solution with an etherifying agent before contacting with cellulose fibers.

CONSTITUTION: The following process is adopted in producing a cellulose ether by reacting an alkaline solution and an etherifying agent with fibrous cellulose in a heterogeneous reaction mixture. That is, (a) in a first region, at least a portion of the etherifying agent required and the required stoichiometric amount of the alkaline solution are mixed at temperature sufficient to suppress reaction between the alkaline solution and the ehterifying agent, (b) the mixture is extracted from the first region, (c) In a second region, the mixture is contacted with the cellulose fiber at an initial temperature sufficient to suppress alkalization of the cellulose, the cellulose fiber is mixed in a heterogeneous reaction mixture containing the required stoichiometric amount of the alkaline solution, the etherifying agent and cellulose, and then the temperature is increased to etherify the cellulose.