A novel single-step approach was developed to prepare large-scale MgAl-LDHs ultrathin nanosheets. The key point of the successful realization was that we employed a high concentration of H2O2. Oxygen molecules, derived from in situ decomposition of H2O2, were speculated to be the decisive factor leading to complete separation of LDHs layers. The ultrathin nanosheets were characterized by XRD, TEM, AFM, FT-IR, and TG-DSC. The results indicated that the thickness of these nanosheets was about 1.44 nm, which was almost in perfect agreement with the theoretical thickness of two LDHs layers. From the TG-DSC curves, the weight loss of these exfoliated MgAl-LDHs ultrathin nanosheets at 500 degrees C was 18.5%, which was much smaller compared to the 32.3% weight loss of unexfoliated MgAl-LDHs. (C) 2012 Elsevier Inc. All rights reserved.