The object was found in an apartment during an ongoing police investigation, said Umeå police spokesman John Forsberg.
According to newspaper Västerbottens-Kuriren police have been interested in the property for some time.
After a decision to raid the place, police entered the apartment at 1pm on Sunday.
Fire chief Krister Andersson told VK’s reporter that some kind of ‘unstable fluid’ was found.
Police cordoned off an area around the building and evacuated nearby apartments. A bomb disposal truck was brought in from Luleå and experts flown up from Stockholm.
The emergency services, including ambulances, were on standby.
Just before 4pm the police bomb disposal experts moved the object from the apartment into the bomb truck. Working with military personnel, police drove the bomb truck to a forest for a controlled explosion.
“The bomb technicians added 125 grammes of explosives for the detonation,” said Forsberg, who on Sunday evening declined to reveal any more details about the object or whether the police had any suspects.
However, he did say that no threat had been reported in connection with the incident and that police had not arrested anyone during the day.
“Removing and transporting the object were the most risky parts of the situation,” said Forsberg.