The aim of this study is to provide a comprehensive view of the issue of open data in Czech cities and thus give the world community an insight into the state of open data in the Czech Republic. It serves as a basis for further research and implementation of open data in urban planning. Its results can be used not only for the benefit of the professional community but can also serve as a basis for decision-making by city authorities in the planning and development of urban space. The open data are therefore integral part of developing smart cities (Ojo, Curry, Zeleti, 2015). This extensive study deals with the issue of the availability of open data in Czech cities and to what extent are they used use in the framework of urban planning and development of urban space. In the context of rapid digitization and technological progress, open data is becoming increasingly important for the effective management and design of urban infrastructure. This study systematically analyses the current state of open data in Czech cities, identifies key aspects of their availability and examines their potential applications in urban planning. The study focuses in more detail on Brno, which is the second largest city in the Czech Republic and provides freely available data on its website data.brno.cz. The first part of the study focuses on the theoretical framework of open data and its significance for modern urban planning. The basic principles of open data are introduced, including the standards and formats currently in use. The advantages of open data in the context of transparent decision-making, citizen participation and sustainable urban development are also discussed. In the Czech Republic, the possibilities of providing and using open data has been more and more discussed in the last ten years, especially at the level of data from state organizations. Nevertheless, the term open data is not understood in the same way by all organizations, when for example PDF format is considered as open data format. At the same time, we also perceive the problem of the completeness, data quality and consistency of open data, as well as missing metadata for easier understanding of lineage. The analysis of available data in specific Czech cities follows up in the second part of the study. The analysis performed includes the identification of existing data sources such as geographic data, traffic information, demographic data and other relevant information for urban planning. Each data source is subject to a detailed evaluation, including assessment of quality, topicality and availability. The Czech regional cities try to provide open data using geoportals., The largest geoportals are data.brno.cz, geoportalpraha.cz, mapy.ostrava.cz, but there exist others. However, state-government institutions also provide data. The geoportal.cuzk.cz and subsequently geoportal.gov.cz might be considered as the largest provider of data (including open data). A large amount of basic statistical data is provided by the Czech Statistical Office, including the last census from 2021, published mainly as open data. Regular hackathons are already organized to increase awareness about open data on these portals, to illustrate the range of possible use of data and the power of making data available to a wide professional and general public. One of the most creative examples can be the Minecraft world derived from a 3D model of the city of Brno. Such an unconventional method may better attract general public to think more about their city and how to contribute to its improvement. In the following part of the study, concrete examples of the use of open data in urban planning are presented. The making available of 3D data of cities became one of the most significant step for the needs of architectural or urban studies. We cannot forget the making accessible of the basic map study (The Fundamental Base of Geographic Data of the Czech Republic) including Digital model of relief, Digital model of surface and orthophoto in the form of open data last year by the State Administration of Land Surveying and Cadastre. Some potential can be hidden in the emerging Digital Technical Map. Different insights onto the location can arise with the optics of the crime rate published by police office. In short, successful projects are described where open data played a key role in optimizing traffic, planning public spaces, and improving the quality of life of residents. Based on these examples, recommendations are proposed for the further development and use of open data in the urban planning environment. In the final part of the study, the challenges and opportunities associated with the implementation of open data in Czech cities are discussed. Potential strategies for improving the availability of open data are presented, incl ...