Abstract The photooxidation of polystyrene films sensitized by anthracene was investigated. The quantum yield of singlet oxygen generation in the polystyrene‐anthracene system, irradiated with light at λ = 365 nm in the presence of oxygen was determined. A kinetic scheme of the photophysical and photochemical processes in the system was proposed and the rate constant of anthracene dimer formation in polystyrene was estimated.