Glycerol is a substance known to humankind for many years now, and among other products, in which composition it is used, are the pharmaceutical, cosmetic, food, paints and varnishes REF _Ref382993082 \r \h [1]REF _Ref382993086 \r \h [6]. The abundance of its supply leads to search for new uses, whether as a plasticizer for biodegradable polymers REF _Ref382993096 \r \h [7], its transformation into other substances like propylene and derivatives or other hydrocarbons [8] [9], the production of hydrogen for energy purposes REF _Ref382993109 \r \h [10], or even direct burning, making glycerol a fuel for boilers, for example. The aim of this work was to investigate the action of the zeolite ZSM5 on glycerol fast pyrolysis at 600°C. The tests were done with a mixture of glycerol-ZSM5 recently prepared using approximately equal volumes of glycerol and the catalyst, and the effluent gases from the fast pyrolysis have been analyzed in a chromatography/mass spectrometry (GC/MS) system. Experiments showed that ZSM5 acts in the pyrolysis of glycerol leading to a large number of substances, from oxygenated products to hydrocarbons, which are part of typical compositions of naphtha, diesel and gasoline petroleum derived products.