X-ray structure deteminations are reported for 2-(3'-tert-butyl-2'-hydroxy-5',6'-dimethylphenyl)benzotriazole (HM-TIN), 2-(3'-tert-butyl-2'-hydroxy-5'-methylphenyl)benzotriazole (HTBM-TIN), and 2-(2',4'-dihydroxy-6'-methylphenyl)benzotriazole (HH-TIN). In contrast to 2-(2'-hydroxy-5'-methyl)benzotriazole (R=H; trade name Tinuvin P (TIN P)) and HTBM-TIN (dihedral angle 5.1 o ) there is no planar arrangement of the bonded benzotriazole and the substituted phenol rings within one molecule in the neat cystal (dihedral angles: HM-TIN, 89.3 o ; HH-TIN, 59.8 o (crystallized at 293 K) and 89.9 o (crystallized at 277 K))