The article proves the existence of a strong correlation between the range of parameters of hydrothermal treatment of oat grain (temperature of moistening, steam pressure, time of moistening) and the moisture content of the grain. The study is based on a multidirectional scheme and allows for conducting analysis of the influence of hydrothermal treatment on the physical properties of oat grain, mainly on its moisture content. The results obtained facilitated the elaboration of a scheme for calculating changes in the geometrical center of grain after it is subjected to steam moistening. It explains a complicated mechanism of changes in the geometrical properties of moistened grain and their effect on the bulky array, which is very important in the proper processing and preparation of grain. The obtained results and their analysis demonstrated practical directions and possibilities of hydrothermal treatment of oat grain before processing. (c) 2008 Elsevier Ltd. All rights reserved.