STO-3G calculated reaction energies of the radical reactions producing C 2 8 H n (n = 1, 2, 3, 4) from the unstable C 2 8 are used to discuss the stabilization of these derivatives. The influence of the nature of various groups X (X is F, OH, NH 2 , Cl, CH 3 , iPr, CN, CF 3 and tBu) on the stabilization of C 2 8 is investigated using the isodesmic reactions in which one or more hydrogens of C 2 8 H 4 are substituted by X. In general, all our calculations predict that C 2 8 is stabilized by the addition of hard monovalent atoms (or groups) such as H and F on the four dangling bonds. When applying the Hard and Soft Acids and Bases (HSAB) principle to these isodesmic reactions, C 2 8 H 3 is predicted to be harder than CH 3 .The stability of C 2 8 H 3 and the localization of its unpaired electron suggest that this molecule may be used as a monomer in a radical polymerization. The stability analysis of the dimer, trimer, tetramer and pentamer (in linear or branched form) shows that these molecules are stable with strong C 2 8 -C 2 8 bonds.