Europe:

The Republic of France, The Republic of Hungary, Swiss Confederation, The Principality of Monaco, The Kingdom of Spain, The Kingdom of the Netherlands, The Republic of Italy, Ukraine, The Federal Republic of Germany, The Republic of Croatia, The United Kingdom of Great Britain and Northern Ireland, The Republic of Bulgaria, The Republic of Poland, The Grand Duchy of Luxembourg, The Republic of Albania, The Kingdom of Belgium, The Republic of Lithuania, The Republic of Montenegro, The Republic of Moldova, The Republic of Belarus, The Russian Federation, The Portuguese Republic, The Republic of Serbia, The Republic of Finland, The Hellenic Republic, The Czech Republic, The Republic of Macedonia, Romania, Ireland, The Republic of Cyprus, The Republic of Austria,The Kingdom of Denmark,The Kingdom of Sweden, The Republic of San Marino, The Kingdom of Norway, The Slovak Republic, The Republic of Turkey, Republic of Estonia, Bosnia and Herzegovina, Republic of Iceland ,The Republic of Malt

Asia:

Philippines, Turkmenistan, Tajikistan, Armenia, Singapore, Sri Lanka, Pakistan, Nepal, Mongolia, VietNam , Kazakhstan, Myanmar, Bahrain, Cambodia, Kyrgyzstan, Malaysia, Laos, Yemen, Japan, Saudi Arabia, Uzbekistan, Palestine, India, Indonesia, Korea, Azerbaijan, Brunei, Lebanon, Georgia, Bhutan, Thailand, Iraq, Oman, Iran, Maldives, Afghanistan, Bangladesh, United Arab Emirates, Syria, North Korea, Jordan, Israel

Africa:

The Democratic People's Republic of Algeria,, The Republic of Congo, The Central African Republic, The Republic of Burundi, The Republic of Togo, The Republic of Equatorial Guinea, The Republic of Benin, The Republic of Djibouti, The Federal Republic of Nigeria, The Republic of Guinea, The Republic of Cape Verde, The Islamic Republic of Mauritania, The Kingdom of Lesotho, The Republic of Mali, The State of Eritrea, The Republic of Seychelles, Union of Comoros, The Republic of Cote d'Ivoire, The Republic of Angola, The Arab Republic of Egypt, The United Republic of Tanzania, The Republic of Senegal, The Republic of Zimbabwe, the Republic of Zambia, The Republic of Namibia, The Republic of The Sudan, The Republic of Kenya, The Kingdom of Morocco, The Gabonese Republic,The Republic of Cameroon, The Republic of Rwanda, The Republic of Tunisia, The Republic of Sierra Leone, The Republic of Madagascar, The Democratic Republic of Congo, The Republic of Uganda, The Federal Democratic Republic of Ethiopia, The Republic of Mauritius, The Republic of Niger, The Republic of Mozambique, The Republic of Guinea-Bissau, The Republic of Liberia, The Republic of Chad, The Federal Republic of Somalia, The Republic of Ghana, The Republic of Botswana, The Republic of South Africa, The Great Socialist People's Libyan Arab Jamahiriya

America:

The Republic of Bolivia, The Commonwealth of Dominica, The Republic of Cuba, Canada, The United States of America (not confirmed yet) The Republic of Costa Rica, The Republic of Guatemala, The Republic of Trinidad and Tobago, The Republic of Argentina, Oriental Republic of Uruguay, Republic of Chile, The Republic of Peru, The Cooperative Republic of Guyana, The Republic of Haiti, Jamaica, The Republic of Suriname, The Republic of Ecuador, Bolivarian Republic of Venezuela, Grenada, The United States of Mexico, The Republic of Nicaragua, The Federative Republic of Brazil

Oceania

New Zealand, The Commonwealth of Australia, The Republic of Vanuatu, The Republic of Palau, The Independent State of Papua New Guinea, The Kingdom of Tonga, The Federated States of Micronesia, The Independent State of Samoa, The Republic of The Fiji Islands, The Cook Islands, Niue, Tuvalu, The Republic of Kiribati, The Solomon Islands

Link to the Official List of participants: http://www.expo2010china.com/expo/english/eu/index.html