This diploma work is aimed at the use of infrared spectrometry by Fire Brigade Units of the Czech Republic. A new portable instrument True Defender FT produced by Ahura was used for this purpose. It was lent by the Institute of Citizens´Protection in Lázně Bohdaneč. The goal of this work is to get acquainted with this instrument and to evaluate its ability to identify unknown substances. Experimental part was aimed at the testing of this spectrometer with the help of model sample set, containing samples from real situations solved by members of Fire Brigade Units of the Czech Republic. Possibilities of mobile infrared spectometer True Defender FT and mobile Raman spectometer First Defender are finally compared.