The thermal property of the pyrolysis reaction of mandarin peel was studied using thermogravimetric analysis (TGA). Thermogravimetric analyses with temperature increases of 10, 20 and 40℃ /min showed large weight losses within the temperature range 150-590℃. Differential thermogravimetric (DTG) analysis curves illustrated that the pyrolysis of mandarin peel was a multi-step process, consisting of water desorption, the decomposition of pectin, hemicellulose, cellulose and lignin, and devolatilization of the residual char. The apparent activation energies ranged between 119 and 406 kJ/mol, depending on the pyrolytic conversion. The pyrolysis products were analyzed, using pyrolyzergas chromatography/mass spectrometry (Py-GC/MS), to evaluate mandarin peel as a renewable source of valuable industrial chemicals. The pyrolysis products of mandarin peel contained high portions of methanol and acetic acid, as well as valuable compounds, such as limonene and vitamin E.