Clean development mechanism' has been established as a strategy to curb the carbon dioxide emissions by the highly developed industrialised countries. The present study aims at analysing the sustainability of this mechanism by comparing its benefits for developed and developing countries. It is seen that the developed countries earn about US $ 865 by buying a certified emission reduction i.e. a ton of carbon dioxide for only US $ 5-15. High carbon dioxide emitting countries, which are not included in the list of developed countries, such as China and India are benefited much more than other developing countries through this mechanism. So, in reality, the developing countries are benefiting very less as compared to the developed countries through this mechanism. It seems as if it is established for the further development of the developed countries at the cost of the poorer ones. Hence, the rhetoric issue of sustainable development appears deemed from the view point of overall development of poorer countries in reality.