The invention relates to a process for preparing solid particles of a phenolic antioxidant from the IRGANOX series in the form of crystals, particularly IRGANOX 1010 and 1098, the crystal particles obtainable by the process, the further processing of the crystal particles, an aqueous dispersion comprising the phenolic antioxidant, novel crystal modifications of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate] (μ-form) and N,N′-hexane-1,6diyl-bis[3-(3,5-di-tert-butyl-4-hydroxypheylpropamide)] (β-form) and aqueous dispersion comprising the new crystal modifications.