MgO/ZnO composite nanosheets with a molar ratio of Mg to Zn of 20/1 were synthesized successfully by a thermal evaporation method. The morphology and structure of the composite nanosheets were characterized and the results demonstrated that the composite nanosheets were polycrystalline with an average thickness of about 5-10 nm. Different from the former reports, it was noted that many composite nanosheets had zigzag edges with angles of 120 degrees. The interim ZnO as a template were introduced to describe the formation of these novel MgO/ZnO nanosheets. Electrochemical experiments showed that these MgO/ZnO composite nanosheets could be used as good materials for immobilization of horseradish peroxidase for the fabrication of efficient H2O2 biosensor. (C) 2015 Elsevier B.V. All rights reserved.