The soldier was the first member of the 1st Infantry Division, which is replacing the 4th Infantry Division, to die in Iraq, said US military spokesperson Maj. Debra Stewart.
The soldier was killed at 9:20 am on Tuesday after the Humvee he was riding in was hit by the bomb in Balad Ruz, just east of Baquba.
A second soldier was wounded in the explosion and airlifted the 31st Combat Support Hospital in Baghdad and was listed in stable condition. The names of both soldiers were withheld pending notification of their families.
The latest death brings to 553 the number of American service members who have died since the Iraq conflict began 20 March. Most of those deaths occurred after President George Bush declared an end to major combat on 1 May.