Ammonium perchlorate particles having strongly adherent wettable coatings are made by treating the particles with stong amines that displace ammonia to form amine perchlorates at the particle surfaces. Silanylamines are preferred since after amination of the perchlorate the silane groups can be hydrolyzed to siloxanes having good wettability by liquid polymeric propellant binders. The coated perchlorate can be used to produce solid propellants having improved mechanical properties and burning characteristics.