AbstractThe synthesis of two new flavin substituted calix[4]arene derivatives, 9 and 10, is described. The first flavin substituted calix[4]arene derivative 9 was synthesized by the reaction of 3‐methylalloxazine (5) with 25,27‐bis(3‐bromopropoxy)‐26,28‐dihydroxy‐5,11,17,23‐tetra(tert‐butyl)calix[4]arene (4) in high yield (92%). The other derivative 10 was prepared from 3‐methylalloxazine‐1‐acetic acid (7) and 25,27‐bis(3‐cyanopropoxy)calix[4]arene (3). All new compounds were characterized by a combination of FT‐IR and 1H‐NMR spectroscopy, and elemental‐analysis techniques.