Eighteen drying experiments on malting barley variety Jarek with initial moisture content ranging from 8to 29 % (w.b.) and exposure time from 0.5 to 5.0 hours were carried out. Drying chamber was not equipped with a fan. so the barley drying was slow. Temperature in the chamber was set up 40, 50, 60 or 70deg;C.In each experiment 11 samples were prepared: one sample for control germination was not treated and ten samples were removing from the chamber at regular time intervals of 0,5 h. Both air temperature in the chamber and grain temperature were measured during the treatment. After treatment each sample was tested on moisture content and after 3 months on germination. The relation between standard deviation of normally distributed death rate and moisture content and grain temperature was determined. Critical temperature for viability reduction of 1 % and 3 % was correlated with logarithm of moisture content and logarithm of exposure time.