Michael Foale and Alexander Kaleri have cut short their work on the outside of the space station because of a fault in the Russian's protective suit.
The Expedition 8 crew - Foale and Kaleri - work outside the platform
The walk marked the first time an entire crew on the station has left the platform to go outside to conduct maintenance work and set up experiments.
Nasa admitted it had at first been sceptical of Russian plans to send the spacemen outside the platform together.
Normally, a third individual is needed to keep a safety watch on spacewalkers.
But with the shuttle fleet grounded and station crews reduced to just two people, this watching brief fell to ground controllers.
The US station commander and his Russian flight engineer were three hours into their mission to swap over experiments and carry out routine maintenance when a temperature control problem with Kaleri's suit was identified.
"It's strangely warm," Kaleri told controllers. A few minutes later, he radioed: "It's amazing. I have rain inside the helmet. I have water on the visor."
Moscow mission control centre flight chief Vladimir Solovyev gave the order for the walk to be terminated and for the crew to return to the station.
Once inside, Foale inspected Kaleri's spacesuit. The cosmonaut was glad to have the suit off. "I feel better now. I feel cooler," he said.
It was found one of the tubes through which water flows to cool the suit, in the stomach area, was bent.
Two spare Russian spacesuits are aboard that Kaleri could use if he and Foale have to go out again. However, no more spacewalks are scheduled for their mission.
The work on the station exterior was not regarded as critical but the list of jobs that need doing to keep the platform in good working order is lengthening because of the moratorium on shuttle flights.
The station's next two-man crew - Expedition 9 - expects to make two spacewalks, conducting far more important work.
Commander Foale had said he was happy to carry out the walk, originally scheduled to take five-and-a-half hours.
He recalled that pairs of Apollo astronauts had made lengthy walks across the Moon's surface in the 1960s and 1970s without anyone staying behind on their lander.