An amperometric test for the antioxidant power (AOP) of biological and food samples is presented. The gist of the method is to measure by linear sweep voltammetry the anodic current produced during the oxidation of the labile species present in the sample and then rationalizing this signal with a mathematical treatment that allows the pseudo-titration of antioxidants (AOs) around a given threshold potential. As a result, the AOP of the sample is calculated. This method allows the discrimination of the most biologically relevant AOs that react rapidly and at low oxidation potentials, from less reactive AOs that are oxidised slowly and at much higher oxidation potentials. This methodology was applied for measuring the AOP of blood, saliva, and natural drinks like orange juice.