Resumen del autor, extraído del trabajo. Determining the process efficiency and business effectiveness is very difficult in the area of special technological processes, as for example, crude oil processing the basic characteristics of which is the production of coupled products. In such technological processes, both direct and indirect costs should be distributed to the bearers of costs by means of the corresponding keys and by using elective division calculation, as the most complex form of accountancy calculation. In oil refineries, the procedure of determining the cost prices of half-finished products (as a measure of efficiency of every refinery unit), and the cost prices of finished products (as a measure of effectiveness of an oil refinery) should be based on the use of corresponding software packet and should consist of several phases. In this Paper, the application of three methods for determining the cost prices of refinery products: Product Density Method, Thermal Value Method and Average Production Cost Method shall be based on the use of an original software packet named "MOR - Management of an Oil Refinery" taking as an example the refinery complex. The procedure for determining the cost prices of oil refinery products will be demonstrated through the following phases: determining the costs per place of costs, determining the cost prices of half-finished products, determining the cost prices of finished products and determining the profit or loss per each individual refinery product. The Paper also points out problems that the oil refinery management has to confront when choosing one of the three mentioned methods, in practice..