Copper phthalocyanine films about 100 nm in thickness were produced by vacuum sublimation. Different heat treatments transformed the layer from the starting alpha- to the beta -structure. The chemical states or the layer were characterized by XPS during this transformation. The measurements from core level peaks and the valence band spectra showed systematic changes. At temperatures above 300 degreesC the Cu detached itself from the chemical bonds in the molecule, the aromatic share of the carbon decreased and new C-N bonds were formed.