The management of the company has at its disposal various theories of capital structure, the aim of which is to provide a clearly interpretable view of the state of the company's capital and to provide instructions and possibilities for its optimization. Descriptive analysis focuses on individual optimization models and points out their characteristics, which also differ from each other. The aim of the diploma thesis is to comprehensively assess the capital structure of a selected business unit based on the selection of a suitable method and other additional indicators. The capital structure is evaluated on the basis of the basic financing rules, which are the golden rule of financing, the current ratio and the one to one rule, and selected ratios evaluating the structure of equity and debt. Among the optimization methods, balance sheet models and the theoretical model according to Miller and Modigliani are applied to a specific company. The results resulting from the calculations are interpreted and evaluated over a period of seven years and then confronted with theoretical recommendations. The suitability and practical applicability of theoretical recommendations is significantly influenced by the fact that the application of these models is possible only under certain conditions and with certain limitations, which is taken into account in the formulation of conclusions for the selected business unit. The results obtained using the M-M model point to the possibility of optimizing the cost of capital by making greater use of foreign capital. The disadvantage is that the model does not consider other factors that are important for the company.