A polymer called plastic is an essential part of our life, due to its wide range of applications. But the main problem with plastic is, it is non-biodegradable in nature and it cannot be easily disposed off. Recently plastic disposal in landfill sites has become a serious environmental problem. Now a days money is spent on new technology to treat the waste plastic. One of the method is to generate useful plastic oil which can be further purified to get gasoline or diesel range hydrocarbon, and can act as alternative fuel, apart from conventional ones. This paper deals with the generation of plastic oils from various plastics like LDPE (Low Density Polyethylene), HDPE (High Density Polyethylene) and PET (Polyethylene Terephthalate). The experimentation is carried out using the parameters: with catalyst (alumina-silica and fly-ash), without catalyst. By pyrolysis and thermal cracking, plastic waste can be decomposed into three fractions: gas, liquid and solid. Pyrolysis is process in which long chain of hydrocarbon breaks into small chain of hydrocarbon. The main consideration is recovery of liquid products which are composed of high boiling point hydrocarbons. © Research India Publications.