These investigations aimed to determine influence of the changes in relative humidity and temperature in storage facilities on the moisture in grain of stored soybean and maize. Soybean ("Podravka 95" variety) and maize ("OSSK 644" hybrid) were stored during 34 days at the temperatures of 0 degree C and 20 degree C, and relative humidity of 55%, 73%, 80% and 98%. At the temperature of 0 degree C and relative humidity of 55% and 73%, moisture in soybean grain decreased, 2.4% and 1.9%, while at the relative humidity of 80% and 98% it increased, 0.2% and 0.6% after 34 days storage. At the temperature of 20 degree C and relative humidity of 55% and 73%, moisture in soybean grain decreased 4.0% and 0.7%, while at the relative humidity of 80% and 98% it increased 0.8% and 2.3%, as following. During 34 days storage at 0 degree C and relative humidity of 55%, moisture in maize grain decreased 0.2%, while at the relative humidity of 73%, 80% and 98% it increased 0.4%, 1% and 1.5%. At the temperature of 20 degree C and relative humidity of 55%, moisture in maize grain decreased 1.5% and at the relative humidity of 73%, 80% and 98% increased, 0.2%, 0.9% and 1.7%. Such investigations enable additional insights into the rate of changes in grain, and the influence on the grain viability in changed storage conditions.