The effect of substitution of the fluorine atoms on spectral, geometric, and photophysical characteristics, as well as proton-donating and proton-accepting properties of free aminopyridine molecules is studied by the methods of electron spectroscopy and quantum chemistry. Energy levels of singlet and triplet states of 4-aminopyridine and 4-aminotetrafluorpyridine are calculated. For 4-aminopyridine and 4-aminotetrafluorpyridine, the band in the middle spectral region is shown to be formed by several electronic transitions of different type and intensity.