Magnesium-aluminum hydrotalcites with a Mg/Al molar ratio of 2 were prepared by coprecipitation or by urea hydrolysis. The as-prepared samples, as well as their activated analogues, were characterized by N-2 physisorption, phenol chemisorption, SEM, XRD, TGA, and DRIFTS. The base-catalyzed transesterification of tributyrin with methanol at 333 K was used to probe the reactivity of the materials. The reconstructed hydrotalcite samples exhibited much higher catalytic activity than the mixed oxides of Mg and Al. Nevertheless, the turnover frequency for the reaction was about two orders of magnitude lower than that of homogeneous sodium methoxide. Variations in the textural properties of the reconstructed hydrotalcite catalysts did not significantly affect the surface base site density or the turnover rate of transesterification. However, the presence of trace water not only enhanced the transesterification reaction rate but also led to severe catalyst deactivation. Characterization of deactivated catalysts revealed a replacement of the interlayer Bronsted base sites with butyric anions, which led to an expansion of the on interlayer distance. (c) 2009 Elsevier Inc. All rights reserved.