It is in every country's interest that the deployment of carbon-change-mitigation technologies (CCMTs) be accomplished at the lowest possible cost to society and that their diffusion be rapid. Reducing barriers to trade is one way to accomplish that, especially given that it is unlikely that every country will become proficient in the production of every CCMT. This study provides a preliminary assessment of the significance of tariff and non-tariff barriers to trade in a representative selection of CCMTs chosen from among those that have been identified by the IPCC and the IEA as having a large economic potential for mitigation, are globally traded, and can be easily adapted to national circumstances. Those examined in the report include: (a) technologies, such as gas-fired reciprocating engines, used in the co-production of both process (or district) heat and electric power (CHP); (b) technologies, such as pipes and meters, used in the production and delivery of heating and cooling at the scale of a city district (DHC); (c) technologies that harness solar energy to heat water or heat or cool the air in buildings (SHC); and (d) relatively energyefficient electric motors and related systems. The study finds that trade in CCMTs faces higher tariffs in some non-OECD countries than in OECD countries. Judging from information provided by exporters in response to a questionnaire, non-tariff measures are common, and in some countries are acting as barriers to trade. Overcoming some of the general measures that impede trade will take time. However, the problems that lax enforcement of intellectual property rights, cumbersome customs-clearance procedures and non-transparent government procurement create for trade in CCTMs should be regarded as providing additional reasons for importing countries to address these issues urgently. Finally, importers may need, at the same time, to examine their domestic policies in order to address behind-the-border impediments to the diffusion of CCMT technologies.