PbO films, grown by pulsed laser deposition (PLD) on two types of substrates (monocrystal quartz and amorphous glass) at different substrate temperatures, are investigated. The overall films’ crystal structure is investigated by X-ray diffraction. The dependence of the film structure on the substrate temperature is considered in the framework of the classical thermodynamic theory. The considerations make clear why films with the alpha-PbO phase solely or predominantly cannot be grown.