Experimental results of studying the variation of the IR absorption spectrum of UF6 in a band centered at 623 cm-1 during the process of UF6 hydrolysis in the atmosphere are presented. The results obtained show that hydrolysis in a volume lasts for a long time, i.e., we can conclude that in the case of UF6 emission to the atmosphere, its free hexafluoride lives in air for a long time. These results confirm the data of indirect measurements on characteristic times of the reaction based on scattering of laser radiation by aerosol particles produced at the hydrolysis.