Due to the growing need for continuous and smooth operation of cranes, we shall follow the development of technology and upgrade individual components of the crane. Each downtime of the crane means a loss of revenue for the respective company, therefore companies are trying to ensure the smooth continuous operation of cranes. Frequency converters have become an indispensable element in the operation of cranes. The main purpose of this diploma is to present the operation and modernization of the crane Cattaneo CM90S4. Moreover, due to increase of usage of the named crane on the market, we have also indicated the sectors where the use of this type of crane is the most frequent. Cranes have become much more sophisticated and practical, and therefore they are an indispensable element in all major industries and construction sites. Due to the increased use of cranes, the state had to provide an appropriate technical legislation for this area. The mentioned legislation is described in the first chapter. The second chapter presents the most common types of cranes, their performance, robust operation, their most common defects, their protection and the conditions for their positioning. In the third chapter of the thesis we have focused on the use, operation and the type of frequency converters. The crane Cattaneo CM90S4 and its components are described in the chapter four. We focused on the frequency converters Omron Varispeed F7 and Yaskawa VS – 606V7 in the chapter five and six. They were used to upgrade the crane Cattaneo CM90S4. Chapter seven describes the installation of the above mentioned frequency converters and input of the parameters. In the future it is expected that the use of frequency converters will continue to grow, as it ensures lower power consumption and greater robustness of operation.