Developing countries are particularly vulnerable to adverse impacts and threats of climate change. Improvement of GHG inventories in the Asia-Pacific region is an essential element to prioritize countermeasures against climate change. The degree of development of GHG inventories in the Asia-Pacific region has large variety. However, forum for exchange of experiences and information to develop good GHG inventories is not established enough. It is frequently pointed out that the common issues of GHG inventories in these countries are insufficient applicability of the default emission factors in the IPCC Guideline and the lack of accurate activity data. This project consists of the pilot studies and the workshops. This pilot studies will pursue training in Japan, establishment of sustainable inventory development system and studies on country/regional emission factors including field measurements in Thailand and Cambodia. In the workshops, the direction of pilot studies and the results of them will be discussed. The accomplishments of the pilot studies will be shared by the participating countries of the workshops to establish more reliable emission factors and more involvement of ASIA-PACIFIC countries with the international activities on GHG inventories.