Abstract: A process for the preparation of a cellulose ether by reacting in a heterogenous reaction mixture an alkaline solution and an etherifying agent with a fibrous cellulose. The total of the required stoichiometric amount of the alkaline solution and at least a portion of the etherifying agent required in producing the cellulose ether are admixed (e.g. in a mixing nozzle) at sufficiently low temperature to suppress reaction between the alkaline solution and the etherifying agent. The admixture is then contacted with the cellulose fibers, preferably by spraying the admixture thereupon. Additional of the etherifying agent if required is then added to the reaction mixture, and the heterogenous reaction mixture is agitated and reacted at an initial temperature below 40.degree. C. sufficient to produce alkalization of the cellulose. Thereafter the temperature is increased above 40.degree. C., preferably incrementally or gradually up to about 100.degree. C., preferably to 80.degree. C.