International policies to reduce carbon dioxide emissions may have major macroeconomic impacts, which EGEM, a macroeconomic/energy model, is designed to simulate. In this paper, an energy demand model is used to compare the impacts of carbon and energy taxes on CO2 emissions in eight OECD countries. EGEM consists of an econometric model of en- ergy demand, integrated into an international macroeconomic model (GEM: Global Econometric Model). GEM has been developed and maintained jointly by the London Business School and the National Institute for Economic and Social Re- search (NIESR). Energy sector equations were esti- mated for total fossil fuel energy consumption, which is then divided into three shares for coal, gas and oil, as functions of energy prices, GDP, a time trend and other determinants. In each case cointegration tech-