The solid oxide catalysts derived from waste shells of egg, golden apple snail, and meretrix venus were employed to produce biodiesel from transesterification of palm olein oil. The shell materials were calcined in air at 800 degrees C with optimum time of 2-4 h to transform calcium species in the shells into active CaO catalysts. All catalysts showed the high biodiesel production activity over 90% fatty acid methyl ester (FAME) in 2 h, whilst the eggshell-derived catalyst showed comparable activity to the one derived from commercial CaCO(3). The catalytic activity was in accordance with the Surface area of and the Ca content in the catalysts. (C) 2009 Elsevier Ltd. All rights reserved.