Thermal pyrolysis has earned a significant reputation in the recovery of valuable chemicals, especially petrochemical-based fuels from various materials, including biomass and plastics. Of many available technologies, flash pyrolysis was preferred in the present work, owing to its minimal heat- and mass-transfer limitations and better control on process conditions. The focus of the work is toward efficient conversion of waste plastics into gaseous products, consisting primarily of alkanes, alkenes, and aromatics. Lab-scale experiments were performed using a flash microreactor to determine a favorable reaction temperature that would result in the maximum yield of olefins, primarily the monomer ethylene.