MgO nanosheets, nanodisks, and nanofibers were synthesized by a hydrothermal method with the aid of suitable surfactants. The nanosheets and nanodisks exposed the (1 1 1) facets mainly whereas the nanofibers exposed a mixture of the (1 1 1), (1 0 0), and (1 1 0) planes. The total number and the surface density of the basic sites followed the order nanosheets > nanodisks > nanofibers. When being used to catalyze the Meerwein-Ponndorf-Verley reaction between benzaldehyde and ethanol, the nanosheets and nanodisks showed much higher reaction rates than the nanofibers, primarily because of their large numbers of surface basic sites that might be linked to the preferential exposure of the {1 1 1} facets. (C) 2014 Elsevier B.V. All rights reserved.