Thermal analysis combined with composition analysis has been used in this work to identify evolved gas when burning household waste. Thermogravimetry (TG) coupled with Fourier transform infrared (FITR) spectroscopy and mass spectrometry (TG-FTIR-MS) offers structural identi.cation of compounds evolved during thermal processes. Carbon, hydrogen, and nitrogen elemental analysis and XRD offers raw materials information. All these combined can help to evaluate the chemical pathway for the degradation reactions by determining the decomposition products. For comparison purposes, emitted species concentrations are measured with multiple-sensors when burning household waste in a lab-scale .uidized bed combustor. There is excellent agreement between the two different approaches. The measured results also provided some insight into burning household waste as an energy source in large-scale incinerators.