Two protesters associated with the environmental activist group held up signs saying "rethink, reuse, recycle" on top of the Palau de Congressos de Catalunya in Barcelona, where the Mobile World Congress was being held. It happened around 6.40pm local time.
A Samsung representative then confiscated the sign, only to see the same protesters pull out another sign.
After they were escorted away, two more Greenpeace members began to rappel down the side of the building to put an even bigger sign up, one that covered the entire edifice.
A Samsung representative held the sign to stop it from unfolding, and it was eventually taken down.