Large amounts of waste acids with high acidity and arsenic levels are produced during pyrometallurgy of nonferrous metal sulfide ores, in which the treatment of arsenic remains a problem. In this study, copper powder was used as a reducing agent and synergized with iodine ions to effectively remove arsenic from waste acids. The influences of stirring speed, copper powder particle size, sodium iodide/copper powder dosages, and reaction temperature on the removal efficiency of arsenic were investigated. The results showed almost complete removal of arsenic under the optimal conditions: 600 rpm stirring speed, copper powder particle size < 15 mu m, molar ratio I:As = 5, molar ratio Cu:As = 8, reaction temperature 40 degrees C, and reaction time 90 min. The kinetics studies indicated that arsenic removal was controlled by chemical reaction with apparent activation energy of 42.39 kJ.mol(-1). The morphological and structural characterizations of dearsenization residues showed surface of copper particles with double covering-layers. The interior covering-layer constituted the formation region of As(0), the phases of which were As and As-Cu intermetallic compounds, while the main product formed in exterior covering-layer was identified as CuI.