Abstract: Spent hydrochloric copper chloride etching solution used in production of printed circuit boards for etching non-galvanized printed circuits is continuously or cyclically regenerated by spraying spent etching liquid from an interconnected etching machine, as with mist projectors, into an upper area of an enclosed regeneration housing, which is also provided with an oxidating gas selected from oxygen, chlorine and a mixture of oxygen and chlorine. The chemical regeneration reaction takes place within the falling mist and a regenerated etching liquid falls to the bottom of the regeneration housing from where it is pumped back to the connected etching machine or station.