The esterification of triethylene glycol (TEG) with methacrylic acid (MAA) was carried out over various solid acid catalysts and the results were compared with conventional acid catalysts. Among the catalysts studied, heteropolyacids showed higher activities than the conventional acids. These were attributed to the acidity of the catalysts. A systematic investigation was carried out for the esterification of triethylene glycol with methacrylic acid over phosphotungstic acid without any free radical inhibitor. The effects of catalyst concentration, alcohol/acid molar ratio and temperature were also studied. Parameters such as activation energy, reaction enthalpy and reaction entropy were derived for the above reaction over phosphotungstic acid in the temperature range of 353-383 K. The obtained results were also compared with silicotungstic acid. (C) 2004 Elsevier B.V. All rights reserved.