Fast co-pyrolysis of Goynuk oil shale (GOS) with low density polyethylene (LDPE) was investigated. The aim of the research was to determine the distribution of volatile products and conversion of blends at different temperatures and time intervals. Pyrolysis of oil shale, LDPE and co-pyrolysis of oil shale-LDPE blend of the total carbon ratio of 1:1 were performed by using the fast pyrolysis method in an isothermal pyrolysis reactor. Volatile organic products eluted from the reactor were collected at different temperatures and time intervals by using a special sampling technique. Fast pyrolysis products were analyzed by capillary gas chromatography. In the aliphatic fraction of pyrolysis products, n-paraffins and 1-olefins were classified by their carbon number. The effect of co-pyrolysis on conversion of total organic carbon into volatile products was identified by determination of the experimental and the hypothetical mean values. Possible synergetic effect was investigated by comparing the results on fast pyrolysis of GOS and LDPE. The effect of co-processing of GOS with LDPE was determined by calculating the difference between experimental and hypothetical mean value of conversion of total organic carbon into volatile products. The experimental conversion of the blend to volatile hydrocarbons was found to be lower than hypothetical mean value of conversion at co-pyrolysis, and thus, no synergetic effect was observed.