In Pathfinder, a monk has a power which lets him spend a point of his Ki Pool to increase his AC Dodge Bonus as a swift action.
Can he do it even when it isn't his turn?
a monk can spend 1 point from his ki pool to give himself a +4 dodge bonus to AC for 1 round
Combat is measured in rounds. During an individual round, all creatures have a chance to take a turn to act, in order of initiative. A round represents 6 seconds in the game world.
A Swift Action consumes a very small amount of time, but represents a larger expenditure of effort than a free action. You can perform one swift action per turn without affecting your ability to perform other actions. In that regard, a swift action is like a free action. You can, however, perform only one single swift action per turn, regardless of what other actions you take. You can take a swift action anytime you would normally be allowed to take a free action. Swift actions usually involve spellcasting, activating a feat, or the activation of magic items.