The present invention provides a powder coating composition comprising A) 30 to 90 wt % of at least one glycidyl-functionalised (meth)acrylic resin as film-forming binder, B) 30 to 90 wt % of at least one cross-linking agent (hardener) for the binder, C) 0.01 to 20 wt % of particles selected from the group consisting of aluminium oxide Al2O3 and aluminium hydroxide Al(OH)3 particles having an average particles size in the range of 0.1 to 10 μm, and D) 0.05 to 50 wt % of at least one coating additive, and optionally, pigment and/or filler, the wt % based on the total weight of the powder coating composition, providing coatings with improved smoothness and high scratch resistance, and surprisingly, gloss and transparency of clear coatings with high quality.