Effect of polypropylene (PP) and polyethylene terephthalate (PET) on lignite pyrolysis is studied in this work. Experiments are conducted in the temperature range of 400–700 °C in a tubular reactor. PP and PET are blended with lignite (M.K.P. lignite, Bursa, Turkey) in the polymer ratio of 33%, 50% and 67% (w/w), respectively. Tar, gas and char yields are calculated and plotted against to the temperatures they obtained for each experimental run. A remarkable synergetic effect between lignite and polymers is also found. The possible reasons of this variation are discussed. Analysis of the tars obtained by different experimental conditions is conducted by GC–MS technique. High yields of benzoic acid and biphenyl are obtained during the pyrolysis of PET and PET:lignite.