Production and utilization of producer gas from mixed plastic wastes were investigated in a pilot-scale moving-grate gasification process. A 500 kW(th) moving grate gasifier was developed, including a flame assisted tar reformer and sequential gas cleaning processes comprising a gas cooler, bag filter, and wet scrubber. The cleaned producer gas, composed mainly of hydrogen, carbon monoxide, carbon dioxide, and methane, was used in a 30 kW(e) gas engine to generate power. Optimal operating conditions of the integrated system were investigated for various parameters As a result, producer gas with a higher heating value of greater than 10 MJ/(N m(3)) and a cold gas efficiency of more than 55% was obtained under oxygen blown conditions. Due to the flame-assisted tar reforming with oxy-combustion of natural gas, the hydrogen content was significantly increased, resulting in an increase in the syngas caloric value and a decrease in the gas cleaning load downstream. In addition, the performance of the syngas power generation engine was tested with the slipstream of the producer gas. A power output of greater than 20 kW(e) and a power generation efficiency of about 22% were obtained.