With the aim of increasing the accuracy of humidity measurement in bulk materials with application of the dynamic thermal vacuum method within the range above 20 % it was suggested to use temperature curve parameters of the vacuumized sample which characterize moisture freezing in the material. The paper offers analytical dependences describing correlations between the volume of water in the vacuumized sample before crystallization begins and parameters of the temperature curve and initial moisture content in the material as well as experimental research results that prove the adequacy of the model offered.