[en] Highlights: • The ranking of different types of power plants with different super efficiency methods are the same. • Combined cycle power plants are more efficient than steam and gas power plants. • Gas power plants are less efficient than steam and gas power plants. • The efficiency of combined cycle power plants has improved over time. • The efficiency of gas and steam power plants decreases or remains constant over time. Nowadays, with the ever-increasing development of the communities, the demand for different forms of energy like electricity has drastically increased. Hence, attention to energy efficiency, especially electricity, seems necessary. Different approaches exist for calculating the efficiency and ranking decision-making units (DMUs), among which data envelopment analysis (DEA) and particularly super-efficiency (SE) method is of the most important ones. In this study, the efficiency of various types of thermal power plants (steam, gas and combined-cycle) has been measured in Iran from 2011 to 2019 using three SE models which are introduced by Anderson-Peterson [1]; Lin-Chen [2] and Li, Jahanshahloo and Khodabakhshi [3]. The efficiency ranking of different types of power plants in three different super-efficiency methods is almost similar. Comparison of the efficiency of combined cycle, steam and gas power plants shows that combined cycle power plants are more efficient than other power plants and gas power plants have the lowest efficiency. An examination of the efficiency score of power plants over time shows that the efficiency of combined cycle power plants has improved over time, while in other power plants this has not happened and some have experienced a reduction in efficiency.