The current study evaluated the effect of powder fractions based on particle size on the chemical composition of macronutrients such as proteins and sugars, on phytochemical properties (total content of polyphenolic compounds, vitamin C and antioxidant activity), on preservation capaci-ty (water activity), reconstitutability properties (water absorption capacity and water solubility index) and physicochemical properties (particle size distribution and moisture content) of black-thorn berries (Prunus spinosa) powders. The fruits were separated from the plant material and seeds, dried and then ground using a FRITSCH PULVERISETTE 19 universal mill for hard mate-rials. Eight fractions were obtained after sieving on seven sieves with different mesh sizes, such as: 1 mm, 0.8 mm, 0.630 mm, 0.450 mm, 0.315 mm, 0.200 mm, 0.125 mm. The grinding/sieving pro-cedure was effective in separating Prunus spinosa powder into sufficiently different size classes. The maximal moisture content and water activity were 5.61% and 0.250 respectively, show the good preservation from a microbiological point of view and ensure prevention the oxidation of bi-ologically active compounds of blackthorn berries powders. For samples with reduced particle sizes, reconstitutability was greatly improved. Total phenolic content, protein content, carbohy-drates and antioxidant activity showed significant improvements for some particle size classes compared to the unsieved sample. Vitamin C presented a semnificative content for the fraction with particle large sizes, precisely because they did not undergo intense degradation processes. Therefore, the technique of grinding and successive sieving proved effective in enhancing the physicochemical and functional characteristics of powdered blackthorn berries, particularly for smaller particles.