When regulating GHG emissions at the country or product level, it is critical to determine the GHG emissions from electricity consumption. In this study, we calculated production-based and consumption-based CO2 emission intensities of electricity for the OECD (the Organisation for Economic Co-operation and Development) countries during 1990-2008. We examined the impact of annual development, allocation procedure in combined heat and power production, and electricity trade on CO2 emissions. The studied factors significantly, yet highly variably, influenced the results for many countries. The consumption-based CO2 emission intensity of electricity differed significantly from the production-based intensity for some European OECD countries such as Switzerland, Norway, Slovakia, and Austria. As the use of the production-based method in assessing, verifying, and monitoring the GHG performance of specific products can be highly misleading, the use of consumption-based methods are preferable. The absolute value of CO2 emissions embodied in electricity net imports accounted for more than 5% of the overall national CO2 emissions in at least some of the years studied for 13 European countries. The electricity trade and the related GHG emission leakage may increase in the future if effective emission reduction and regulation measures are not more widely implemented. (C) 2012 Elsevier Ltd. All rights reserved.