Copyrolysis of a turkish lignite with low- density polyethylene ( LDPE) is conducted in a tubular reactor. The effect of experimental conditions ( temperature of 400- 700 C, catalyst, LDPE contents of the mixture are 33, 50, and 67 wt %) on the formation of tar, gas, and char and their effects on the formation of phenol are investigated. The catalysts used are red mud ( which is a waste product of an aluminum factory in Turkey), zeolite ( Linde type A ( LTA)), and K2CO3. Tar evolution is determined to be increased significantly by increasing the LDPE content of the coal- LDPE mixture during the pyrolysis. The effect of adding LDPE to the coal on the gas generation is not remarkable. An increase in temperature leads to increased gas yields. Phenol and phenol derivatives are the obstacles for the complete conversion of lignite to tar and gas. To investigate this negative effect of phenols on the yields, the phenols found in tar from coal pyrolysis are detected by gas chromatography- mass spectroscopy ( GC- MS), and it is observed that phenolic structures detected in the tar obtained by individual pyrolysis of coal are dramatically decreased by adding polymer to the coal. The use of catalysts during the copyrolysis procedure leads to improved gas generation. The possible reasons of these variations are discussed. A remarkable synergetic effect between lignite and LDPE on the tar yields is also observed.