This study uses the dynamic DEA model to evaluate inter-temporal efficiency for executive efficiency based on fossil-fuel CO2 emissions in OECD countries and China. The significant difference between this study and previous studies is the assumption of energy stock, defined as a carry-over intermediate linking different terms. This model provides a ratio as a standard for energy stock to be adjusted, which is based on the assessment of the optimal quantity of energy stock. In addition, we explore output and input inefficiency indicators in the model to figure out the sources of operational inefficiency. The empirical result of the average overall scores' efficiency is 0.78 for 2000-2010, and the adjustment ratio in energy stock shows that most countries exhibit efficiency improvement. The inefficiency ratio of the carry-over intermediate shows an average of 5.29%, which is positive. These 27 countries should thus increase the number of energy stock to improve their efficiency. Our period of study included a series of global energy reforms, such as the commitment to the Marrakesh Accords, which encompasses the implementation time frame of the Kyoto Protocol that started in 2008 and ended in 2012. (C) 2017 Elsevier Ltd. All rights reserved.