This contributions shows with a series of ab initio MP2 and DFT (BP86 and B3-LYP) computations with large basis sets up to cc-pVQZ quality that the literature value of the std. enthalpy of depolymn. of 1/4Sb4F20(g) to give SbF5(g) (+18.5 kJ mol-1) [J. Fawcett, J. H. Holloway, R. D. Peacock, D. R. Russell, J. Fluorine Chem. 20 (1982) 9] is by about 50 kJ mol-1 in error and that the correct value of DrH Degdeploy. (1/4Sb4F20(g)) is +68 +- 10 kJ mol-1. We assign DrH Degdeploydepoly., DrH Deg, DrG Deg and DrG Deg values for SbnF5n with n = 2-4 and compare the results to available exptl. gas phase data. Esp. the MP2/TZVPP values obtained in an indirect procedure that rely on isodesmic reactions or the highly accurate compd. methods G2 and CBS-Q are in excellent agreement with the exptl. data, and reproduce also the fine exptl. details at temps. of 423 and 498 K. With these data and the addnl. calcn. of [SbnF5n+1]- (n = 1-4), we then assessed the fluoride ion affinities (FIAs) of SbnF5n(g), nSbF5(g), nSbF5(l) and the std. enthalpies of formation of SbnF5n(g) and [SbnF5n+1]-(g): FIA(SbnF5n(g)) = 514 (n = 1), 559 (n = 2), 572 (n = 3) and 580 (n = 4) kJ mol-1; FIA(nSbF5(g)) = 667 (n = 2), 767 (n = 3) and 855 (n = 4) kJ mol-1; FIA(nSbF5(l)) = 434 (n = 1), 506 (n = 2), 528 (n = 3) and 534 (n = 4) kJ mol-1. Error bars are approx. +-10 kJ mol-1. Also the related Gibbs energies were derived. DfH Deg([SbnF5n+1]-(g)) = -2064 +- 18 (n = 1), -3516 +- 25 (n = 2), -4919 +- 31 (n = 3) and -6305 +- 36 (n = 4) kJ mol-1. [on SciFinder (R)]