A series of heteropolyacid (HPA) salts as catalysts were prepared and characterized. Transesterifications of trimethylolpropane (TMP) were carried out using these catalysts. The influence of organic cations and heteropolyanions on the reaction, optimization of reaction conditions, and catalytic reusability were investigated. The results show that the heteropolyacid (HPA) salts present a self-separation performance after reaction, which can be easily recovered and quite steadily reused as demonstrated by a eight-run recycling test. Moreover, the pyridinium with PW12O403- as the anion ([PyBS](3)PW12O40) showed the best catalytic performance among the heteropolyacid salts for the transesterification of trimethylolpropane with various methyl esters. (C) 2010 Elsevier B.V. All rights reserved.