A cold etchant, esp. for Cu(alloys) and in particular printed circuits, is composed of an aq. soln. of H2SO4 and CrO3 and additionally HNO3 and/or HF and/or alkaline fluorides and FeCl3. Tinned Cu, Fe-Ni, Fe-Cr, constantan as well as Cu (alloys) may be etched. The etchant is used cold and no poisonous fumes are given off. Harmful slimes are not produced. The concns. can vary within relatively large limits. The compsn. may also contain HCl. Pref. embodiment the compsn. contains per 1.: 0.15 1. HNO3 at 40 degrees Be, 0.15 1. H2SO4 at 60 degrees Be, 0.15 1. FeCl3 at 36 degrees Be and 0.15 kg. CrO3.