A natural feature in changing hardness and strength of coals, their solid products of thermal processing and briquettes based on them is of great theoretical importance, because these parameters can indirectly characterize the properties associated with the characteristics of their origin, their petrographic composition and degree of their metamorphism. The main aim of the research is to study the microhardness of brown coal and coal.  The methods. Before carrying out the experimental studies, a granulometric analysis of raw material used was carried out using a granulometric analyzer AS Control 200 with a set of sieves from 4 mm to less than 125 µm. The sample mass of 1 kg, the amplitude of 2 mm/year, classification 10 minutes. Determination of humidity of the studied objects was carried out in a drying Cabinet according to SS 11014-2001 «Coals brown, stone, anthracite and oil shale. Accelerated methods of moisture determination». Ash content was determined according to SS 11022-95 «Solid mineral fuel. Determination of ash content». The yield of volatile components was determined by SS Р55660-2013 «Solid mineral fuel. Determination of the yield of volatile substances». Briquetting of coal and shale fines was carried out on the laboratory hydraulic press PGL-20. Briquettes were made at a pressure of 15 MPa without wetting. Briquettes were made of the same parameters: height 10 mm, diameter 15 mm. Heat treatment of the studied briquettes was carried out in two regimes: regime no. 1 «without aging». Six crucibles with briquettes were placed in the muffle furnace with the initial temperature corresponding to the room temperature. Then they were heated to 100 °С, one crucible was got out of the furnace and the rest ones were continued heating to 200 °С. The operation was repeated to temperature in the furnace chamber equal to 600 °С in increments of 100 °С without exposure at the final temperature; regime no. 2 «Hot furnace». The crucible with the briquette was loaded to the muffle furnace heated to the appropriate operating temperature (100; 200; 300; 400; 500; 600 °С); it was kept there for 30 minutes and removed. To determine microhardness of the samples the ultramicrotome SHIMADZU DUH-211S was used for testing hardness (microhardness) of the material. Results. The study of microhardness of brown coals and coal briquettes from this material showed that: for brown coal when using both heating regimes, the microhardness value decreases to a temperature of 200 °C from 57,928 to 44,907 N/mm² (regime 1) and to 46,905 N/mm² (regime 2), with temperature rise to 300 °С, the microhardness value begins to rise to 51,048 and 51,247 N/mm² for regime 1 and 2, respectively. Further heating leads to increase in microhardness to 64,879 N/mm² for the first regime and decrease to 32,797 N/mm² for the second regime; for coal in the heat treatment regime 1 microhardness value increases from 4,894 to 7,157 N/mm², and in the heat treatment regime 2 falls to 2,921 N/mm².