The outing with colleague NASA astronaut Tim Kopra is to replace a failed part that regulates power from the space station's solar arrays, the European Space Agency said in a statement.
There are eight of the voltage regulators -- known as sequential shunt units -- aboard the ISS so the job is not critical to the orbiting outpost's performance.
But the task has been on the to-do list since a failure of the voltage regulator "compromised one of the station's eight power channels last November," NASA said in a statement.
Peake (43) arrived at the space research lab on December 15 for a six-month stay.
