Oxidative stress has been associated with a wide spectrum of diseases in the modern era. Antioxidative therapy has demonstrated significant potential in prevention and therapy of cancer, cardiovascular and neurodegenerative diseases. However, molecular forms of natural phenolic antioxidants lack efficiency due to low bioavailability, compatibility, and stability. The aim of the present study was to preserve and improve the properties of phenolic antioxidants immobilizing them on sol-gel derived γ-AlOOH (pseudoboehmite) nanoparticles. The prepared formulations with gallic, caffeic, and ferulic acids are in the form of hydrosols. Results show that modified AlOOH nanoparticles exhibit good colloidal stability at wide pH range and in presence of background electrolyte. Carboxylic groups of phenols play an active role in interaction with pseudoboehmite slightly changing its surface properties. Modification of AlOOH nanoparticles shifts its isoelectric point from basic to more neutral values, changes pKa values and lowers number of acid-base centers. The studied pseudoboehmite-phenol systems show high radical scavenging activity, pronounced membrane-protective and antioxidant properties on cellular and non-cellular models in vitro, enhancing efficiency of phenolic acids. The prepared nanoantioxidants can be used to develop delivery systems of various therapeutic agents and pave a way to new therapeutic strategies for treatment and prevention of socially significant diseases.