In the present article an attempt is made to identify and give a comparative analy-sis of some key, in the author's view, systemic and structural components of the power system of the South Caucasus states – Azerbaijan, Armenia and Georgia. The main attention is paid to the formation, institutionalization  and further evolution of their statehood throughout the post-Soviet period, concentrating on the disclosure of main provisions of their constitutions related to the form of the state system. It is shown that during the period under review, Armenia and Georgia have moved from presidential to presidential-parliamentary to purely parliamentary republics, while Azerbaijan – from presidential to super-presidential republic with elements of hereditary power transfer.