Visegrad Four (V4) countries have undergone a series of changes in the energy sector since the fall of the Communist regime. These countries embarked on the way of market reforms and restructuring of their economies. At the same time, they were able to maintain growing GDP, while increasing their energy efficiency and decreasing the greenhouse gas (GHG) emissions. However, emission decrease is attributed mainly to the closure of the heavy industry, as it is the case of former Czechoslovakia and not because of the introduction of effective policies. The structure of the energy mix of the V4 countries is path-dependent, heavily influenced by the communist period. V4 countries are dependent on imported and domestic fossil fuels, especially coal in the Czech Republic and Poland and natural gas and oil in the whole V4. Three countries (the Czech Republic, Hungary and Slovakia) inherited also the nuclear sector that continues to be the key in the low-carbon electricity sector. Poland plans to join the nuclear club as well and is planning to develop its first nuclear power plant by mid-2030s. From the point of view of the renewable energy sources (RES), V4 countries opt for their traditional sources (biomass and hydro), while the penetration of wind and solar energy is rather modest and the countries are not even close to the EU targets (see full report).