The article describes the terms and definitions of energy service, nature and elements of energy service contracts which are mentioned in the science literature. The article characterizes the usage of energy service contracts of different countries, features and problems of energy service contracting development in Russia. The leaders in a global energy service are Germany, France, Great Britain, Austria, USA, China and other. Energy service contracts have become a highly effective method of energy saving in developed countries. As a rule, they have a highly developed body of law, strong state support and special programs for financing this activity. State energy policy played an important role in stimulating ESCO activity in various markets. The volume of a global energy service market is more than 24 billion dollars (2015): 55% of China; 26% of USA; 11% of the European Union countries. More than 2.3 thousand of energy service companies are functioning in China. The article points that energy service has become a new and complex business in Russia. Russian's Association of Energy Service Companies "RAESCO" gives the following figures: 96 companies are registered 702 contracts were performed in 2016. The total volume of the market is 7.4 billion rubles (0.13 billion dollars). Most ESCO contracts in Russia are for 5 years, and they generally are small. ESCOs also are concerned about costly and risky tender procedures. The most complex element in Russia is a development of organizational and legal instruments to attract investments in energy service.