Reaction of iodine with carbon acids with a pK(a) below 13 leads to iodine-containing molecules that are effective oxidants for copper while being stable and having a high solubility. The identities of these compounds and other reaction products is elucidated by the use of liquid chromatography-mass spectrometry and UV/visible analysis. The mechanism of polishing copper with slurries containing these oxidants is examined by electrochemical experiments and shown to be similar to the oxidation of copper with iodine where a CuI film forms a weakly passivating film by dissolution and precipitation and is removed mechanically.