Display omitted •Model-free integral kinetics method and analytical TGA–FTIR were conducted on pyrolysis process of PKS.•The pyrolysis mechanism of PKS was elaborated.•Thermal stability was established: lignin>cellulose>xylan.•Detailed compositions in the volatiles of PKS pyrolysis were determinated.•The interaction of biomass three components led to the fluctuation of activation energy in PKS pyrolysis. Palm kernel shell (PKS) from palm oil production is a potential biomass source for bio-energy production. A fundamental understanding of PKS pyrolysis behavior and kinetics is essential to its efficient thermochemical conversion. The thermal degradation profile in derivative thermogravimetry (DTG) analysis shown two significant mass-loss peaks mainly related to the decomposition of hemicellulose and cellulose respectively. This characteristic differentiated with other biomass (e.g. wheat straw and corn stover) presented just one peak or accompanied with an extra “shoulder” peak (e.g. wheat straw). According to the Fourier transform infrared spectrometry (FTIR) analysis, the prominent volatile components generated by the pyrolysis of PKS were CO2 (2400–2250cm−1 and 586–726cm−1), aldehydes, ketones, organic acids (1900–1650cm−1), and alkanes, phenols (1475–1000cm−1). The activation energy dependent on the conversion rate was estimated by two model-free integral methods: Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) method at different heating rates. The fluctuation of activation energy can be interpreted as a result of interactive reactions related to cellulose, hemicellulose and lignin degradation, occurred in the pyrolysis process. Based on TGA–FTIR analysis and model free integral kinetics method, the pyrolysis mechanism of PKS was elaborated in this paper.