A fluidized bed reader was used to study the production of gases from municipal solid waste (MSW) pyrolysis at high nominal temperatures (700-850 degrees C). Biomass decomposition followed by tar cracking reactions took place inside the reactor. Yields of 10 pyrolysis products (methane, ethane, ethylene, propane, propylene, acetylene, butylenes, hydrogen, carbon monoxide, and carbon dioxide) as a function of operating conditions were analyzed. The results were compared with the data obtained by the pyrolysis of MSW in a Pyroprobe 1000 where tar cracking is small. Correlations between the yields of the products analyzed and those of methane are presented and their evolution is discussed.