The aim of the study is to determine the mercury content in hard coal, randomly taken from the USCB and in by-products of hard coal mining (fresh mining waste), i.e. aggregates (gangue) and hard coal sludge and mining waste from the Siersza dump (weathered waste). The 34 samples were intended for analysis. The total mercury content and the amount of mercury leaching from solid samples was determined. The percentage of the leaching form in the total element content, i.e. the level of mercury release from the material (leaching level), was also calculated. The amount of mercury leaching was determined by a static method using a batch test 1:10. The highest possibility of leaching mercury is characterized by weathered waste from the Siersza dump and slightly lower analyzed hard coal from the U pper Silesian Coal Basin (USCB). For hard coal samples, the total mercury content is between 0.0275–0.1236 mg/kg. However, the amount of mercury leaching from coal samples is 0.0008–0.0077 mg/kg. The aggregate is characterized by a higher total mercury content in the finest fraction 0–6 mm, within 0.1377–0.6107 mg/kg and much lower in the 80-120 mm fraction, within 0.0508–0.1274 mg/kg. The amount of elution is comparable in both fractions and amounts to 0.0008–0.0057 mg/kg. Coal sludge has a total mercury content of 0.0937–0.2047 mg/kg. L ow leaching values of 0.0014–0.0074 mg/ kg are also observed. Weathered mining waste has a total mercury content of 0.0622–0.2987 mg/kg. However, leaching values from weathered waste are much higher than from fresh mining waste. This value is 0.0058–0.0165 mg/kg. In the hard coal extracted from U SCB, the leaching level is 4.7% on average. Mining waste is characterized by a large variation in the proportion of mercury leaching form and the differences result from the seasoning time of the samples. Waste or by-products of hard coal production, such as aggregates and coal sludge, show a mercury washout form at an average level of 1.7%. The proportion of leachable form in weathered waste increased strongly to 7.3%. Elution characteristics vary for different groups of materials tested. Factors such as the type and origin of samples, their granulometric composition and the seasoning time of the material are of fundamental importance and demonstrated in the work.