Lt. Gen. Valery Asapov died after sustaining a "fatal injury" in the "sudden Daesh mortar shelling," the ministry said.
"Lt. Gen. Valery Asapov died in the Syrian Arab Republic as a result of the Daesh shelling," the statement said.
According to the ministry, the deceased serviceman will receive a state award posthumously.
In early September, the Syrian government troops, backed by Russian airstrikes, broke a three-year Daesh blockade to the west and south of Deir ez-Zor. On Monday, the Syrian Army crossed the Euphrates River with the support of the Russian Aerospace Forces near Deir ez-Zor, knocking militants out from a number of settlements, and are currently developing an offensive eastward.