30 SEPT 2026History
What time did Chernobyl explode? 26 April 1986, 01:23 local time
Reactor 4 at Chernobyl exploded at 01:23 Moscow time on 26 April 1986. In UTC that is still 25 April, 21:23.
Short answer: 26 April 1986 at 01:23 local time (Moscow summer time, UTC+4) at the Chernobyl nuclear power plant in Soviet Ukraine. In UTC that is 25 April 1986, 21:23.
What happened
During a safety test on reactor 4, the power rose uncontrollably. Explosions at about 01:23:40 destroyed the reactor and the building above it, and a fire released radioactive material across Europe for days. Two workers died that night; 28 plant staff and firefighters died of acute radiation sickness in the following months. The nearby town of Pripyat was evacuated the next afternoon.
Why the UTC date is different
The Soviet Union used Moscow time, four hours ahead of UTC in summer 1986. So the minute of the explosion falls on the evening of 25 April in UTC.