Ivan Kronov was a loyal communist agent during the days of the Cold War. He was the subject of a military experiment to create a warrior who could eliminate Captain America and Bucky. By 1954 the project was a complete success and Kronov was transformed into the electricity powered super-agent known as Electro. Electro was then smuggled into New York City, where he was to attack Captain America and Bucky when they made their public appearance in a parade that was taking place that day. Altering an electronic billboard to present a death threat to Captain America, Electro goaded the hero into a rooftop battle leading the three combatants to battle it out on a large typewriter display. There Captain America and Bucky fended the villain off with the massive typewriter. However, Electro managed to jolt Bucky and use him as a hostage as his electrical charge was running low. He used Bucky as a shield as he attempted to inch closer to a dynamo that could recharge his powers. Realizing what was going on, Captain America activated a sprinkler that doused Electro as he reached for the dynamo which caused a short circuit that seemingly electrocuted Kronov to death.
However, Electro was not truly dead, as later he was revived by one of his comrades Albert Malik who was posing as the Red Skull at the time. Malik was seeking to obtain Adolf Hitler's long lost strong box, believing that it contained the secrets to a powerful weapon. The Red Skull used a device to recharge Electro bringing him back to life. Believing that the strong box was being kept in the United Nations Building the pair attacked the UN in the hopes of recovering it. This led to another conflict with Captain America and Bucky. During the course of the battle, Bucky had struck Electro with a car seemingly killing him again. The Red Skull theorized that it was possibly the electrical charge in the car battery, but did not stay to find out having obtained what he thought was the lock box and abandoned his comrade. Electro's sacrificed would turn out to be in vein as the strong box turned out to be a fake.
Although Electro has not been seen since, it remains to be seen if he is truly dead or if he can be revived once more.
Electro is in essence a living dynamo capable of carrying a nearly lethal electrical charge in his body for up to 24 hours before needing to recharge. Electro can channel this electricity through his body. At least in one case, Electro was brought back to life by being recharged.
Electro is required to recharge his electrical supply every 24 hours in order to maintain his powers. It also appears that conflicting electrical charges can disrupt the energy that Electro retains in his body -- for example he gets his power from an electrical dynamo, and the electrical charge of a car battery appeared to have disrupted his powers and seemingly killed him.