The physicochemical properties of 3-methacryloyloxy-9-diethylamino-5-dicyanomethylene-5H-benzo[a]phenoxazine and its vacuum-deposited thin films as well as its modified thin films (phase and chemical compositions, film microstructure) have been studied. Changes in the vapour phase content of the phenoxazone-5 derivative have been investigated as a function of the boat evaporator temperature. The chemical structures of the transformation products have been established. Thin films of 3-methacryloyloxy-9-diethylamino-5-dicyanomethylene-5H-benzo[a]-phenoxazine show good light-sensitive and masking properties and are suitable for submicron patterning under UV exposure at lambda = 266 nm.