The Ohio State Highway Patrol said Darrell Young, 24, of Athens was driving on State Route 56 in Athens County on Friday afternoon when he drove off the left side of the road and hit a tree.
His 19-month-old son, Tyler Young, was pronounced dead at the scene. Darrell Young was ejected from the truck and taken to a nearby hospital in critical condition.
He later died at a hospital.
The crash is under investigation.