The effect of pre-devulcanization and temperature in waste tire pyrolysis are investigated on pyrolysis time, yield and properties of residual Heavy Fraction Pyrolytic Oil (HFPO). A comparative pyrolysis of usual Ground Tire Rubber (GTR) and a commercial devulcanized ground tire rubber, (known as Reclaim Rubber-RR) is performed in a static-bed batch reactor at 400-600 degrees C and the oil is distillated to light and heavy fractions. Chemical composition studies show higher amounts of aromatics in HFPO than light fraction. As a novel approach, a relationship between isotherm at max temperature and pyrolysis temperature is presented in this work. Pyrolysis time for RR is approximately half of GTR at same temperatures due to RR devulcanized nature. The solid yield is larger for GTR than RR and decreases by temperature. The liquid yield for RR is larger than GTR. Pyrolysis time and liquid yields of GTR and RR approach to each other at higher temperatures. Kinematic viscosity and flash point are larger for GTR oils in comparison with RR. FTIR shows by increasing temperature the ratio of alkanes/aromatic (I-2952/I-1456) decreased for HR and increased for HG. So it can be said that both oil contain similar functional groups at different concentrations depending on temperature. H-1 NMR and C-13 NMR spectra shows oils are a mixture of aromatics, alkanes, alkenes, alkynes and ethers or alcohols, which exist in different concentrations. Gel Permeation Chromatography (GPC) shows that pyrolysis of GTR produces oil which is heavier and broader in Mw distribution in comparison with pre-devulcanized sample (RR). Elemental analysis shows similar elemental composition of HFPOs. (C) 2013 Elsevier Ltd. All rights reserved.