The contract on forming of Energy Community of Countries of Southeast Europe has been signed in Athens. In this way, the conditions have been created for defining of electric power and natural gas markets. By forming of Energy Community of Countries of Southeast Europe, the unique, stable and regulatory framework for crossborder trade in energy has been created, because the countries from this region accepted general rules in field of energy that relate to environment protection and competition. Forming of Energy Community of Countries of Southeast Europe, which encompasses market of about 150 million people, is historical event. Over 21 billion EUR will be invested only in power supply sector in the following 15 years. The contract with European Commission have been signed by Serbia and Montenegro, Croatia, Bosnia and Herzegovina, Macedonia, Bulgaria, Romania, Albania and temporary mission of United Nations in Kosovo.