Total atomization energies and heats of formation of silole, its radicals, cation and protonated forms were calculated using G4 and CCSD(T)/CBS (cc-pV(n+d)Z, n = 2-6) methods. Experimental data for silole are not available. Using Delta H-f degrees(Si,298 K) = 107.9 kcal/mol, Delta H-f degrees(298 K) are predicted (+/- 2 kcal/mol): silole: 44, radical cation: 249, Si-radical: 79, C-protonated: 218 and C-alpha-H radical: 47. Both homolytic and heterolytic dissociations of silole take place at Si. Both C-protonation and hydrogen atom addition preferentially occur at the C-alpha-site. Thermochemical parameters of silole are: PA = 190 kcal/mol, IE = 8.9 eV, BDE (Si-H) = 86 kcal/mol and deprotonation energy DPE = 362 kcal/mol. (C) 2013 Elsevier B.V. All rights reserved.