Nuclear Man was created by Lex Luthor from a strand of hair containing Superman's DNA, made into a "genetic stew" which was birthed into a living being when Superman threw the nuclear missile containing the device that had the "stew" into the sun. He had about the same powers as Superman, and had nuclear radiated claws which can poison a man. If he's not in sunlight, he will become powerless. In Superman's first encounter with Nuclear Man, he caused a number of disasters to distract Superman, such as causing a tornado in Kansas, blowing out parts of the Great Wall of China, causing a volcanic eruption in Italy, trying to detonate a nuclear missile in the heart of Moscow, and dropping the Statue of Liberty into the heart of a city and pierced the Kryptonian's skin when he tried to save the Statue of Liberty, causing him to lose his powers and his health. As he continued to be Lex's pawn, he fell in love with Lacy Warfield. After Superman restores himself with the use of the energy module from his star ship, he had a rematch with Nuclear Man. Their fight brought them to the moon where Nuclear Man buries the Man of Steel in the moon, and kidnaps Lacy. Superman then stopped Nuclear Man for good by causing a sudden solar eclipse when he moved the moon in front of the sun, then dropped him into the heart of a nuclear reactor where he would become an abundant source of energy.
Nuclear Man is extremely powerful: he is completely incapable of exhaustion, for one. He possesses superhuman strength that rivals Superman, as well as incredible speed, reflexes and durability. He is capable of rendering himself immune to Earth's gravity, and can also survive in the vacuum of space flawlessly. In a fight, Nuclear Man is extremely dangerous, being the only person in the Superman films up until Man of Steel to truly outmatch Superman in combat, and very nearly kill him. Nuclear Man's main ability are his intensely potent talons that can inflict a fatally poisonous injury upon whomever they come into contact with.