Today it is increasingly evident that data is the new determining element in the economy and society. Digital data is essential resources for economic growth, competitiveness, innovation, job creation and social development. For well-founded decisions, real data containing all the necessary information are required. Public organizations are obliged to collect and store vast amounts of data. However, the question arises: who has access to them and for what purposes are they used for? Open Data has become increasingly prevalent both on organizational and national levels. By making the datasets available to the public, institutions have become more transparent, efficient and more economical. There are EU and national strategies and programs to support open public administration by providing an appropriate legal environment and recommending practical measures. Freedom of information guarantees the accessibility of public data. However, accessibility is blocked by several challenges and obstacles, such as traditional approaches, legal constraints, practical and technical problems. The aim of this paper is to interpret the basic concepts of open government data, and present some of the problems of Hungarian data policy, legal regulations and practical implementations.