Pilot-scale tests were conducted at MEFOS for the production of zinc oxide from Electric Arc Furnace (EAF) dust using a DC arc furnace with a hollow electrode suitable for the processing of fine-grained materials. The association of halides in Electric Arc Furnace (EAF) dust and zinc oxide fume before and after water leaching was investigated by XRD, SEM, and TEM analysis. In EAF dust, chlorine and fluorine were found to exist primarily as NaCl, KCl, and CaF2. After water leaching of the zinc oxide fume the halide concentrations were reduced to about 200 ppm Cl and 200 ppm F, mostly in the form of CaF2 and chlorine-containing silicate phases.