This paper employs data envelopment analysis to evaluate energy utilization efficiency between China and Taiwan from 2002 to 2007. The most important contributions of this paper are the clear description of the systematic process of energy utilization efficiency, the efficiency comparison between China and Taiwan, the remarkable demonstration of their outputs through two non-desirable outputs (CO2 emissions and SO2 emissions) in the data envelopment analysis framework, and the valuable results and insights gained from the application of economic development and environmental protection. Empirical results show that the Eastern region of China enjoy higher energy utilization efficiency than the Western region. Energy utilization efficiency in Taiwan is higher than that in the Eastern region of China. In China, CO2 emissions were 11.28% greater than they should be (from 2002 to 2007). By contrast, CO2 emissions in Taiwan were only 1.50% in excess of what they should be since Taiwan began conducting an uninterrupted energy-saving policy and a CO2 emission regulation policy (Bureau of Energy, Ministry of Economic Affairs, 2009). Finally, this study employs the business strategy matrix constructed by the Boston Consulting Group (BCG Matrix) to illustrate individual evidence of the relationship between economic development efficiency and greenhouse gas efficiency. (C) 2009 Elsevier Ltd. All rights reserved.