Two pieces of uniform ZnO thin film samples made by MOCVD were treated with hydrogen peroxide (H2O2) solution and oxygen, respectively. It is observed that the UV emission peak (3.30 eV) becomes stronger, the green emission peak (2.36 eV) becomes weaker, and the green emission peak shifts from 525 nm (2.36 eV) to 500 nm (2.48 eV). A new UV emission peak occurs at 383 nm (3.24 eV) in one sample, which has a green emission peak at 525 nm after it was treated with 30% H2O2. For the other sample, which has no obvious green emission peak, the UV emission peak (3.29 eV) becomes stronger, a new UV emission peak emerges at 383 run (3.24 eV), and a new weak green emission peak appears at about 500 nm (2.48 eV) after it was treated with 30% H2O2. It was found through integral interference microscopy that the surface of samples are smoother and some crystal boundary lines appears that are either parallel to each other or intersect into an angle of about 60degrees. No new hexagonal pits or other shape pits emerge after both of the samples were treated with 30% H2O2, from which it can be inferred that the 30% H2O2 does not corrode the ZnO situated at the crystal lattice, although it can corrode the excess Zn and some impurities localized at the crystal boundaries. (C) 2004 Published by Elsevier B.V.