Alpha-phenyl-n-tert-butyl nitrone (PBN) shows its major effect by scavenging free radicals formed in the ischemia. and it has the ability to penetrate through the blood brain barrier easily. The in vivo stability of PBN is very low and when administered systemically, it has a mean plasma half life of about three hours. Therefore, formulations which are able to prolong the plasma residence time of PBN are of major interest, because oxygen radicals are usually continuously formed under pathological conditions. In this study, PBN, a nitrone compound having neuroprotective properties, was encapsulated in chitosan (CS) and chitosan-poly(ethylene glycol) (CS-PEG) nanoparticles for treatment of diseases such as stroke, in which sustained free radical production is reported. The nanoparticles were characterized through particle size determination, zeta potential, encapsulation efficiency, surface morphology determinations and in vitro release studies. The surface morphologies were evaluated by transmission electron microscopy (TEM) and nanoparticles having spherical shapes were characterized. The particle size distribution was between similar to 97 nm and similar to 322 nm; and the zeta potentials varied between similar to 9 mV and similar to 33 mV. Size of the nanoparticle formulations was important for the release of PBN from nanoparticles. The quantitative determination of PBN has been evaluated by a validated analytical HPLC method. The presented chitosan-based nanotechnology opens new perspectives for testing antioxidant activity in vivo.