Forty-nine people died in that explosion. Fifteen others were killed in an explosion at a nearby restaurant.
Invisible Children, an aid group that helps child soldiers, identified Henn, 25, a native of Wilmington, Delaware, as one of those killed.
The organization's blog posted a tribute to Henn calling him a self-less man who raised thousands of dollars to put Ugandan children in school.
In the comments sections on the blog, one person posted this about Henn:
"I cannot begin to tell you how sad we are to hear of the loss of Nate," the post from Scot Wolfe reads. "We will see him again just beyond those pearly gates and I am sure he will be surrounded by Ugandan children."
Police believe an al-Qaida-linked group is behind the double blast. Several other Americans were among the wounded.
Secretary of State Hillary Rodham Clinton is "strongly condemning" the explosions. Clinton says the United States will work with the Ugandan government "to bring the perpetrators of this crime to justice."