Abstract: Compositions in fine powder form that can be obtained by means of a dry co-grinding process of an at least ternary mixture consisting of an active substance, a carrier and at least one auxiliary co-grinding substance, wherein the active substance is constituted by one or more micronutrient substances with particular antioxidant activity. Such compositions have shown a significant increase in active substance antioxidant power in comparison to solutions of equal active substance content. Said effect is particularly useful for uses for active substances included in antioxidant compositions in the pharmaceutical, cosmetic and dietary-nutritional fields.