The paper discusses the use of fossil fuels and the process of their extraction in Poland. Hard coal used on a daily basis in one of the Polish CHP (combined heat and power) plants was described, followed by monthly measurements of coal parameters. Daily and total analyzes of the obtained measurement results of hard coal were carried out in accordance with the applicable standards. The differences in the values of coal from the same source but imported at different time intervals are shown, which result from the weather conditions and the method of hard coal storage.. At the end, the work was summarized with conclusions. Negative correlations occurred between ash content and calorific value, heat of combustion and volatile matter, as detailed in this article. The research on the properties of hard coal was carried out in winter. The reaserach were performed on the basis of compliance with PN.