The woman brought the grenade to a recycling depot in Stockholm on Saturday, the Swedish news agency TT reported.
When police arrived at the scene, they determined that the item the pensioner dropped off was a grenade meant for a grenade-launcher. They removed the grenade from the recycling depot for destruction.
On March 1, the Swedish government enacted a law that allows citizens to turn in weapons to police without the fear of any potential prosecution.
Since then, police have received a number of grenades, including one that dated back to World War I