This master’s thesis commences with a brief history of energy diplomacy and how it is interrelated with foreign policy, national security and energy security. Afterwards it provides an insight into the complicated field of energy diplomacy, viz how the major energy players perceive energy security, what energy policies have adopted so far and how they attempt to cope with their energy dependence. At the core of the thesis lie the cases of the European Union, United States of America, China and Russia. In each specific case, the level of their energy dependence is analyzed and solutions are provided in order to amplify energy security and reduce energy dependence. Last but not least, the role of energy transition is outlined and how it affects energy diplomacy and how it has redefined the term energy security.