The one-electron oxidation of ascorbate produces the ascorbyl radical (A), that has beenproposed as a marker of oxidative stress either in vitro, or in vivo in numerous systems. Theapplication of a simple kinetic analysis allowed us to estimate the steady state concentration of A.These data were successfully compared to experimental values obtained using ElectronParamagnetic Resonance (EPR) in rat brain under physiological conditions and the response tostress due to sub-chronic Fe overload. The main objective of this chapter is to further explore theinformation presented in a previously published manuscript employing a simple kinetic modeldeveloped to estimate A steady state concentration to other Fe-dependent oxidative conditions inrat brain.Fil: Piloni, Natacha Estefanía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Puntarulo, Susana Ángela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; Argentina