The accident happened at midday on Friday when the man climbed into a cauldron at the Eraso soup factory in Lübeck to clean it.
The lid suddenly closed while the 36-year-old was still inside and began to fill with steam as part of the disinfection process.
A doctor confirmed that the unidentified man had been cooked to death.
Erasco makes soups, stews and other foods at the Lubeck factory. The company has been in business since 1873.
"The circumstances of how such an accident could have occurred have not yet been explained," said Lubeck police spokesman Detlef Ridel.
via Worker cooked to death at German soup factory - Telegraph.