Abstract: In a process for producing epoxy resin with low EHC-content there is added to a continuous flow of the chlorine-substituted starting material continuously, with all reaction parameters constant, a dehydrochlorinizing agent, e.g. NaOH, in an amount approximately the stoichiometrical equivalent of the predetermined EHC-content of the starting material. Ionically bound chlorine is removed from the epoxy resin. A stream of a bypassing portion of the epoxy resin is subjected continuously, with brief periodical interruptions, directly after removal of the ionically bound chlorine, to fluorescence-exciting X-ray irradiation and the total chlorine fluorescence is detected, thereby automatically continuously determining the total chlorine content.