The releasing behavior of chlorine (Cl) and fluorine (F) during agricultural waste pyrolysis was investigated using a fixed-bed pyrolysis system with pyrohydrolytic-ion chromatography and thermodynamic equilibrium calculation. Agricultural waste contains a large amount of Cl-bearing species, among which approximately 30% is easily released with biomass drying. During biomass pyrolysis, Cl-bearing species evolve out rapidly to the gas phase, and higher temperature is favorable for the releasing. The releasing process can be divided into two ranges: the fast evaporating range (200-600 degrees C) and slow evaporating range (600-1000 degrees C). F shows similar transforming behavior. However, higher temperature is preferred for the release. Thermodynamic simulation shows that Cl mainly exists as KCl(g) at higher temperatures (>600 degrees C) with some HCl(g) and K2Cl2(g) as intermediate species at lower temperatures (<600 degrees C), whereas F mainly releases as SiF4 at higher temperatures (>500 degrees C) with SF5Cl being the dominant F-bearing species at lower temperatures (<500 degrees C). (C) 2014 Published by Elsevier Ltd.