On the beginning of the paper Katowice Coal Holding Inc. is characterised - one of major consumer of electrical energy in Poland that in the second part of 2002 year entered the competitive electrical energy market. Subsequently particular stages of the entry are talk over including modernisation of measuring and calculating systems, creation of computer and transmission systems and creation of Central Power Operator's Room. Much attention is paid to peculiarity of internal settlement including internal balance market and internal power stock exchange in order to keep fair allotment the cost of deviation to particular plants. Lack of integrity in the rules and instructions and lack of assistance in entering the market from the side of energy companies are also shown. It has been proved that active joint into process of evolutionary changes gives positive economic results.