The present invention relates to a powder paint composition comprising at least (a) a thermosetting polymer having functional groups capable of reacting with .beta.-hydroxyalkylamide units (b) a compound comprising .beta.-hydroxyalkylamide units and (c) a deceleration agent, capable of reversibly blocking the functional groups of polymer (a). The deceleration agent is present in an amount sufficient to block at least 9% of the total amount of functional groups of polymer (a). The present invention relates also to the use of a specific amine compound as a deceleration agent in a powder paint composition.