The behaviour of steel at high fire temperatures is an essential element in the design of steel structures. Although steel is a non-combustible material, its mechanical properties decrease significantly with temperature, especially if critical values are reached. Therefore, it is necessary to provide the necessary protection of the steel elements against fire, which can be achieved by various materials such as coatings, paints, thermal insulation materials, board systems, concrete coatings, etc. In this way, the temperature rise in the steel elements is reduced below a critical value. In this work, an analysis of the temperature development through the cross section of a steel profile of type HE180B without protection and with protection is carried out. The materials used for protection are calcium-silicate boards, cement-based plaster and concrete boards, each of which was further analysed with three different thicknesses. The fire is defined by the standard ISO 834 fire curve for 120 minutes. The analysis was performed using a two-dimensional model to calculate the development of temperatures, TasefPlus. The obtained results showed that the minimum thickness required to prevent the critical temperature rise in steel profile below the 550 ° C for the calcium silicate plate was 30 mm, for the concrete board 50 mm, and for the cement-based plaster 45 mm.