The device, called an astronomical compendium or astrolabe, disappeared from the Gotha Museum in Gotha, Germany, sometime in 1945.
"This was a one-of-a-kind scientific device," said Brian Kennedy, president and director of the Toledo museum. "It's sad to see it go, but it's not ours."
Americans occupied Gotha during the war and many of the museum's collections were moved in 1945 to the former Soviet Union once authority over the area was transferred from United States.
The astronomical device, though, was one of the few items from the museum that didn't end up in the Soviet Union. Instead, it landed in the hands of a New York art dealer before it was sold for $6,500 in 1954.
The museum in 2013 received a letter from the director of the Gotha Museum, saying that it found out about the piece in Toledo and believed it was theirs.
Kennedy said they reviewed documentation, including photographs, from the Gotha Museum and determined that the piece on display in Toledo was "most likely one and the same."
The two museums then reached an agreement to get the historically valuable piece back to its rightful owner, Kennedy said.
"We've recognized there's been a cultural shift in how museums conduct themselves," he said. "There's much more scrutiny in how museums obtain their objects and transparency now."
This is the fourth time since 2010 that the Toledo museum has returned art that belonged to someone else.
Last year, the museum announced that an 11th-century Indian statue was likely stolen from an Indian temple. The museum bought the small bronze statue from a New York dealer now charged in India.
The institution also returned a mermaid figure stolen during World War II to a German museum in 2011 and an illegally looted ancient water jug to Italy in 2013.