This thesis examines cost accounting and financial reporting in oil industry’s companies. The main goal of this thesis is monitoring and analysis of the costs and financial reporting on the example of the company Jadranski naftovod d.d. (Oil Pipeline of the Adriatic, share holding company). In order to achieve this basic goal, these specific goals are set: 1) Define the term cost, classify costs, analyze costing accounting methods, and present the main features of the oil industry in the world; 2) Define the regulatory framework for business and financial reporting in the oil industry and analyze the specifics of financial reporting in the industry; 3) Analyze accounting cost monitoring and financial reporting on the example of companies from the oil industry. Different research methods are used. Professional national and foreign literature is analyzed using a deductive approach. In addition, methods of analysis and synthesis, abstraction and concretization and generalization and specifications are also used. An empirical study was conducted for this thesis on the example of one enterprise of the oil industry. The subject of the research is Jadranski naftovod d.d. (JANAF, Oil Pipeline of the Adriatic, share holding company). Secondary data used in the paper were collected from the financial statements of the company in question. By analyzing financial reports, a conclusion is drawn that the company achieves exceptional business results in 2018 and 2019, although a noticeable decrease in profits is observed in 2019, due to the overhaul in JANAF refineries. The company managed to finance entire business year of 2019 from its own financial assets. The company has a positive net cash flow from operating activities, given the exceptional business results in 2018 and 2019. For the company to continue the trend of successful business, it is necessary to be systematic and precise in cost control to avoid any unwanted business situations in the future.