Tungsten (W) and tungsten diboride (WB2) nanolayers can be used for the fabrication of field emitters in microelectronics due to the low work function and high thermal stability of these materials. Fourier transform infrared spectrometry (FTIR) can be used for the characterization of compounds containing polar bonds. W and WB2 have weakly polar or non-polar bonds. In order to apply infrared spectrometry for the characterization of W and WB2 layers, a chemical modification via thermal oxidation can be performed. It is possible to achieve oxidation of nanolayers and the formation of polar bonds at elevated temperatures by varying the content of oxygen and water, and then the FTIR spectra of the oxidation products can be measured. W and WB2 layers with a thickness of 150 nm were deposited on the Si/SiO2 substrate by the magnetron sputtering technique. The synthesized layers were oxidized in a thermal analysis device SEIKO EXSTAR 6300 under various gas flow conditions (varying the content of oxygen and moisture). Prior to and after oxidation, FTIR spectra were registered.