Sea ports and associated port areas are the backbone of the world trade and the centers of transport systems. Every country which has a port area on its territory, through the development of numerous economic activities along the coast, seeks to multiply their influence on the economy as a whole. States seek to regulate a sustainable and competitive port system through legal regulations and strategic documents. The method of management of the port area and its organization depends on the geographical characteristic of the port system and the importance of the maritime area. For the management and control of the port area of the state, port authorities are most often established. The port authority represents a hybrid organization in which on the one hand the owner of the port achieves the strategic goals of the port, while the economic functions within the port area are assigned to the concessionaires. In this way, the port authority acts as a public institution representing state interests, and on the other hand, a private entity allows business according to economic principles with the aim of generating profits. One of the fundamental issues in the operations of port authorities is financial sustainability. States are facing increasing budget allocations and there is a need for financial independence for port authorities. The graduate thesis evaluates financial operations of non-profit public institutions engaged in the construction and maintenance of the port area. In total, 28 port authorities were established in the Republic of Croatia, of which 22 are under county administration and 6 are under state administration. Inter alia, the results show how much revenue they earn, how much they are funded by donations, and how financially self-sustaining they are. The paper used methods of analysis, description, comparison and synthesis for this study.