As a substitute for diesel and considered a renewable energy, rapeseed-based biodiesel has attracted increasing attention in China. The present work to estimate energy cost of rapeseed-based biodiesel in China is based on embodied energy intensities for various inputs out of a recent extended input output analysis for Chinese economy, and the accounted life-cycle process of biodiesel production includes four main stages as agricultural crop production, transportation, industrial conversion characterized by alkali-catalyzed transesterification and wastewater treatment. Due to the low rapeseed yield and intensive chemical fertilizer use in China, the overall energy cost of rapeseed-based biodiesel is estimated at 1.1 times of its biodiesel energy output, corresponding to a negative energy return, with essential policy-making implications, in contrast to the positive ones usually reported in previous researches. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.