Energies, geometries and electronic structures of cyclopentadiene (1), silole (2), germole (3) and their radical anions (RAs) 1a–3a have been studied by quantum-chemical methods at the G2(MP2, SVP) and DFT B3LYP/6-31G(d,p) levels. According to G2(MP2, SVP) calculations 1–3 have negative electron affinities (EAs) equal to −1.09, −0.06 and −0.15 eV, respectively, and hence their RAs are unstable in the gas phase. 1,2,3,4-Tetraphenylcyclopenta-1,3-diene (4) and 2,3,4,5-tetraphenylsubstituted-2 (5) and 3 (6) and their radical anions (4a–6a) were studied at the B3LYP/6-31G(d)//AM1 level. Substitution of cyclodienes results in significant stabilization of RAs 4–6 because of the effective delocalization of an extra electron within phenyl groups, especially those in positions 2 and 5, so 4–6 all have a positive EA. Our best estimates give for 4, 5 and 6 EA values 0.98, 1.30 and 1.13 eV respectively. The calculated hyperfine coupling (hfc) constants a(H) for radical anions 4a–6a are in a good agreement with experimental values. Variation of group 14 element (C, Si, Ge) in the series 1–3 and 4–6 do not produce a monotonous change of EA and hfc values.