The SrBi2Nb2O9 platelets with a thickness of about 600nm were synthesized by molten salt synthesis method. The treatment of the SrBi2Nb2O9 platelets with hydrochloric acid resulted in the formation of the protonated H1.78Sr0.78Bi0.22Nb2O7 platelets. Through a top-down approach in ethylamine solution, the H1.78Sr0.78Bi0.22Nb2O7 platelets were exfoliated into H1.78Sr0.78Bi0.22Nb2O7 nanosheets with a thickness of about 2.6 nm. The evolution of the structure, composition, morphology, optical, and photocatalytic properties of SrBi2Nb2O9 platelets was studied as it is converted into H1.78SR0.78Bi0.22Nb2O7 platelets and subsequently exfoliated into H1.78Sr0.78Bi0.22Nb2O7 nanosheets. The absorption edge shifts to a lower wavelength accompanied by the protonation and exfoliation. The photocatalytic H-2 evolution of the three samples were evaluated under the irradiation of a 300W Xenon lamp from CH3OH/H2O solution, indicating that H1.78Sr0.78Bi0.22Nb2O7 nanosheets Exhibit 5.5 and 26.2 times higher activity than that of the H1.78Sr0.78Bi0.22Nb2O7 and SrBi2Nb2O9 platelets, respectively. The enhanced activity for the H1.78Sr0.78Bi0.22Nb2O7 nanosheets is mainly attributed to the higher separation efficiency of the photo generated carriers and the larger specific surface area caused by the significant reduction in thickness. (C) 2016 Elsevier B.V. All rights reserved.