In this paper, the effect of meso-substituents nature and solvent properties on the photo-and thermal stability of BODIPYs, was studied. It was found that the replacement of the hydrogen atom in the methine bridge by CH3 group, carboxylic acid residues (CH2)(n)COOH or their esters (CH2)(n)COOCH3 (where n = 3, 4) significantly in-creases the photo-and thermal stability of meso-substituted dyes compared to meso-unsubstituted analog that is in good agreement with the results of NBO analysis. It has been established that the photooxidation process of dyes in solutions proceeds more efficiently in aromatic toluene (in similar to 2-3 times) and, especially, in the electron donor DMSO (in similar to 10 times) compared to non-polar cyclohexane, which is due to the specific solvation of dye molecules by aromatic and polar solvents.
