Oxidation of Cu(CN) 3 2− in water by H 2 O 2 is less documented. The present study investigated the effects of pH, H 2 O 2 dose and CN − /Cu(I) on oxidation of Cu(CN) 3 2− . Furthermore, oxidation of Cu(CN) 3 2− by H 2 O 2 was investigated in the presence of ethylenediaminetetraacetate (EDTA) or pyrophosphate. The results indicated that Cu(CN) 3 2− oxidation was more favored at pH 9.5 and 11.0 than at pH 12.0. With the increase of H 2 O 2 dose, rate of Cu(CN) 3 2− oxidation was accelerated. Oxidation of Cu(CN) 3 2− was accelerated with CN − /Cu(I) decreasing from 4.0 to 2.8. In the presence of EDTA or pyrophosphate, oxidation of Cu(CN) 3 2− was significantly enhanced. 4.0mM cyanide was nearly oxidized by 4.8mM H 2 O 2 in the presence of 1.0mM EDTA. According to UV–Visible spectra variation of Cu(CN) 3 2− solutions, it was found that H 2 O 2 firstly oxidized Cu(CN) 3 2− to Cu(CN) 2 − . The successive oxidation of cyanide from Cu(CN) 2 − led to liberation of Cu(I). Cu(I) was oxidized into Cu(II) with formation of hydroxyl radicals (HO) or Cu(III). H 2 O 2 was decomposed of into O 2 in the process. The strong bonding of Cu(II) to EDTA suppressed decomposition of H 2 O 2 into O 2 and enhanced the effective utilization of H 2 O 2 for cyanide destruction. By contrast, complexation of Cu(II) with pyrophosphate enhanced the catalytic redox reaction (Cu(I)/Cu(II) or Cu(I)/Cu(III)), improving cyanide oxidation. The results provide a possible way to improve treatment of Cu(CN) 3 2− wastewater by H 2 O 2 .