In this work we deal with problems related to thermal insulation of buildings and materials used for this purpose. The bachelor thesis is divided into two parts, theoretical and practical. The theoretical part is a summary of knowledge about the most commonly used thermal insulation materials in terms of legislation and fire protection. Practical part is a summary of the results of experimental work on the evaluation of two thermal insulation materials of mineral wool (Isover CLIMA034) and expanded polystyrene (Isover GREYWALL) in terms of reaction to fire. Based on the results obtained by testing methods according to STN EN 1182 (flammability test) and STN EN 11925-2 (ignition test), the tested materials were classified according to STN EN 13 501-1 + A1 following expanded polystyrene (Isover GREYWALL) to the fire reaction class So E is a combustible material. And the mineral wool (Isover CLIMA034) to class A2-s1, d0 is the inclusion of non-combustible materials, which means that it does not contribute to the development of fire. The results of our experiments are consistent with the results of the manufacturer.