The paper presents experimental results of studies on the temperature dependence of integrated intensities of vibrational bands corresponding to3(GeF6) in M2GeF6IR-spectra. It is shown that unlike Na2GeF6, Rb2GaF6, and Cs2GeF6, where the dependence of intensity on temperature is monotonous, in the case of K2GeF6there exist anomalous temperature ranges of 220-240 and 150-170 K, where the intensity of a band, corresponding to3(GeF2-6) changes abruptly. The study of heat evaluation, heat capacity, unit cell parameters, and intensities of selective reflexes in K2GeF6X-ray diffraction patterns indicates the presence in this compound, as distinguished from others in the seris considerod, of phase transitions of the first order. On the basis of IB,19F NNR, X-rat and calorimetric data, a possible mechanism of polymorphic transformation is discussed.