Active biodiesel production catalysts were derived from waste eggshells by simple calcination in air. The physicochemical properties of the activated catalysts were characterized by XRD, N-2 sorption, CO2-TPD, TGA-DTG, XRF, and SEM, while the catalytic activity was tested in producing biodiesel via transesterification on palm oil with methanol under microwave conditions. The effect of microwave power, reaction time, methanol-to-oil ratio, and catalyst loading was investigated. The experimental results revealed that the catalysts exhibited a high content of CaO (99.2 wt%) with a high density of strong base sites. The catalytic testing demonstrated a remarkable enhancement for biodiesel production using microwaves compared to conventional heating. The maximum yield of fatty acid methyl esters reached 96.7% under the optimal condition of reaction time of 4 min with 900 W microwave power, methanol-to-oil ratio of 18: 1, and catalyst loading of 15%. The results indicated that the CaO catalysts derived from eggshells showed good reusability and had high potential to be used as biodiesel production catalysts under microwave-assisted transesterification of palm oil. (C) 2011 Elsevier B.V. All rights reserved.