It happened at the Drury Plaza Hotel on Percy Drive just after 1 a.m.
The department attributes this system with extinguishing the fire.
The Cape Girardeau Fire Department says the fire was contained to the bathroom, which sustained some smoke damage.
Officials say a guest overcooked food in a microwave, disposed of the food while not aware of any fire, and left the room.
According to authorities, a second guest was in the room at the time and was able to escape unharmed.
There are no injuries to report.
Guests were allowed back to their rooms a couple of hours later.