A set of molecules (2-(2'-hydroxyphenyl)benzoxazol (HBO), 2-(2'-hydroxyphenyl benzothiazole (HBT) and 2-(2'-hydroxyphenyl)benzimidazole (HBI)) exhibiting excited-state intramolecular proton transfer was studied using the polarizable continuum model in low-polar, non-protic solvents (chloroform and carbon tetrachloride), combined with the AM1 semi-empirical molecular orbital method in both gaseous and condensed phase. The heats of formations (Delta H-f) are lowered by the solvent effect, especially in chloroform. The increase in the solvent polarity causes an enlargement of the Stokes shift between absorption and emission.