Police were called to Gardner Close in Eastbourne after the grenade was reported on Monday, June 24.
The grenade was found by resident Ingrid Herron in her loft while she was doing renovations.
She said: “It was a real shock. Police had been called, Haven school and park had to be cornered off until it could be safely removed and sent to be detonated.”
Officers said that the hand grenade was taken to a field and destroyed in a controlled explosion.
In a statement, a spokesperson said: "Officers assisted the Explosive Ordnance Disposal (EOD) team after a suspected Second World War hand grenade was found in a residential property in Eastbourne at about midday on Monday, June 24.
“The EOD team later carried out a controlled explosion on a field off Sevenoaks Road, and have now stood down.”