It is shown that the reactivity of nitrone compounds in spin trapping reactions (addition of short-lived free radicals to the nitrone double bond) can be predicted by means of not very complicated semi-empirical procedures simulating a hypothetical adsorption complex and its further transformation into spin adducts. Thus estimated reaction characteristics (the site of radical addition to a nitrone, stability of the resulting spin adduct, the effect of its geometry on hyperfine splitting constants in the EPR spectra of spin adducts) generally agree with the experimental data available on these nitrones. (c) 2006 Elsevier B.V. All rights reserved.