The paper examines how and to which extent consolidation in the Polish power generation sector has affected the potential for market power over the last 10 years. Although this sector has been undergoing liberalisation (privatisation, introduction of TPA regulations and competition etc.), the consolidation efforts shown by Polish governments have resulted in a significant increase in concentration of both installed capacity and production. The methodology applied in this study includes typical ex-post structural and behavioural measures employed to estimate potential for market power, namely: concentration ratios (for the largest and the three largest suppliers), the Herfindahl-Hirschman Index, entropy, Supply Margin Assessment, the Residual Supply Index and the Lerner Index. Furthermore, an analysis based on the Gini coefficient was employed to obtain an insight into inequalities. The results of this study show that governmental decisions led to a significant increase in the potential to exercise market power held by key power generation companies. Of key importance was the 2007 consolidation, resulting in an increase in the HHI to 1374 (in terms of installed capacity) and 1945 (in terms of electricity production). This consolidation resulted in the creation of the first Pivotal Supplier in the Polish power generation sector in 2008. (C) 2011 Elsevier Ltd. All rights reserved.