Display omitted •Renewable non-edible seeds were used for pyrolysis.•Seven models were used to determine kinetic parameters.•Kinetic reaction data showed good agreement with experimental data.•VZ and DAEM methods produce minimal error compared with others. The present study addressed the kinetics characteristics and pyrolysis behaviour of waste biomass Azadirachta indica (NM) and Phyllanthus emblica kernel (AM) in a thermogravimetric analyzer. Six model-free techniques such as Kissinger-Akahira-Sunose, Distributed Activation Energy Model, Friedman, Coats-Redfern, Ozawa-Flynn-Wall, Vyazovkin and Criado method were employed to evaluate the kinetic parameters at five varying heating rates (10–50 °C min−1). The physicochemical inspection directed that both the biomass had excellent prospects to produce energy and finest chemicals. FTIR study pointed strong evidence of moisture, protein, acid, and aromatics. The average apparent activation energy was found to be 176.66, 193.67, 196.06, 177.32 and 204.23 kJ mol−1 for NM and 184.77, 195.10, 189.95, 186.46, 184.57 kJ mol−1 for AM for KAS, OFW, FM, DAEM and VZ respectively. Further, master plot and thermodynamic study of AM and NM revealed that pyrolysis went through various reaction mechanisms at the time of pyrolysis.