Reactron first appears in The Daring New Adventures of Supergirl #8 (June 1983), in a story written by Paul Kupperberg and drawn by Carmine Infantino.

Recruited by General Sam Lane as part of his Project 7734, Reactron is equipped with a heart made of gold kryptonite and partnered with Metallo.

As part of his participation in Project 7734, Lex Luthor sends a robot double of himself with Brainiac on a mission to attack New Krypton, a new planet in Earth's solar system populated by the survivors of the Kryptonian city of Kandor.

[16] This version is a former nuclear engineer who was exposed to radiation amidst a terrorist attack that Superman thwarted, during which Ben's wife Alyssa died.

Blaming Superman for her death, Ben built an advanced biomedical exo-suit that grants super-strength, the ability to fly, and fire energy blasts.