Police said threats were made towards the couple during a burglary at a property on Melrose Close, Balby, Doncaster during which cash and food was stolen.
A South Yorkshire Police spokesman said: "Just after 10.10pm on Saturday, February 10, it was reported a woman armed with a hammer had entered the property on Melrose Close.
"The woman threatened the couple in the property and made demands for cash before making off.
"A small quantity of cash and food items were taken in the burglary.
"The couple, although they were not hurt in the incident, have been left incredibly scared and distressed by what has happened."
The woman has been described as white, aged around 30, of a slim build, between 5ft 6ins and 5ft 8ins tall and with black, shoulder-length hair.
She was wearing fingerless gloves, a black jacket, black jeans, black boots and a pink bobble hat.
An investigation is currently ongoing into the incident and officers are now appealing for witnesses and information.
Anyone with information is asked call police on 101 quoting incident number 1172 of 10 February.
Anonymous information can also be given to Crimestoppers on 0800 555 111