Ethylcellulose having an ethoxyl content of from 40 to 55 percent and a viscosity of from 1 to 100 mPa's, measured as a 5 weight percent solution in toluene and ethanol at a volume ratio of 80:20 at 25.degree. C., is produced by depolymerization of an ethylcellulose having an ethoxyl content of from 40 to 55 percent and a viscosity of from 4 to 400 mPa's in the presence of gaseous hydrogen halide to achieve a reduction in viscosity of the ethylcellulose of at least 10 percent.