We have presented an accurate theoretical evaluation of reduction/oxidation potentials in the presence/absence of aluminum for a test case redox reaction between DPPH • and hydroquinone. The relevant species' reduction and oxidation potentials have been previously determined experimentally in the absence and presence of aluminum, allowing comparison between experimental and theoretical data provided in this work. To the best of our knowledge, this is the first time that such a comparison has been made in the context of aluminum biochemistry. The results given here support the experimental predictions that aluminum alters the thermodynamics of the scavenging reaction, being able to shift the process from an endergonic situation to a spontaneous exergonic one.