The "human hand grenades" had a short lived career during the Golden Age of Comic Books, reappearing occasionally in reprint form during the seventies, returning in Super Friends # 12, and appearing from time to time in All-Star Squadron and its Post-Crisis sequel, Young All-Stars.
TNT and Dan The Dyna-Mite are the secret identities of chemistry teacher and track coach Thomas N. "Tex" Thomas and his student Daniel Dunbar. While working together with some "radioactive salts", they discover they are charged with atomic energy. Thomas is charged with positive energy, while Dunbar is charged with negative energy. Thomas makes a pair of rings which keeps the energy dormant until they are touched together, at which point the pair gains enhanced strength, speed, and resistance to injury, and the ability to generate different forms of energy. Thomas generates heat, while Dan can generate short bursts of electricity. The series ran through Star-Spangled Comics #23 (August 1943).
TNT was revived as part of Roy Thomas's All-Star Squadron, and its spin-off, The Young All-Stars. After TNT and Dyna-Mite had been active for a few months, they are summoned by the All-Star Squadron to participate in their first general meeting. Their participation seems to have been limited to attending meetings and little else until April 1942, when Liberty Belle, as chairperson of the All-Stars, asks TNT and Dyna-Mite to look into Axis espionage activity in Colorado. Here, they meet future All-Star member Iron Munro, but TNT is killed by Gudra the Valkyrie, a supernatural agent of Adolf Hitler. TNT is posthumously awarded the Medal of Honor, leaving Dyna-Mite to work with Munro and other members of the Young All-Stars. Keeping Thomas' ring, Dan finds he can activate his powers by slamming both rings together.
In 2010's DCU: Legacies #2, TNT and Dyna-Mite are revealed to have been founding members of the Seven Soldiers of Victory. How this retcon affects their histories, such as the previously established death of TNT and Dyna-Mite's Young All-Stars stint, has not yet been revealed.
The latest version of the character is featured in Grant Morrison's Seven Soldiers project. Calling himself Dyno-Mite Dan, Harris D. Ledbetter makes an online purchase of what he believes are TNT and Dan The Dyna-Mite's rings, and joins five other heroes in Seven Soldiers # 0. Sadly, he is killed with the rest of his team. His rings are actually working fakes made by Cassandra Craft.