In this paper, bio-oil production, kinetics analysis, and exergy analysis of Prosopis juliflora pyrolysis are reported. The biomass was segregated into two different particle sizes (< 0.5 mm and > 2.0 mm). Elemental analysis and higher heating value of Prosopis juliflora biomass were estimated. Thermogravimetric analysis of biomass was performed at 5 different heating rates of (5 °C min−1, 10 °C min−1, 15 °C min−1, 20 °C min−1, 25 °C min−1). Thermal degradation of Prosopis juliflora biomass was performed at different temperature ranging from 400 °C, 450 °C, 500 °C, 550 °C to 600 °C. The maximum liquid yield was 17.4% obtained at 500 °C with 0.5 mm particle size. Gas chromatography-mass spectrometry analysis of the Prosopis juliflora liquid phase showed the presence of petroleum compounds. Iso-conversion method is used to establish the kinetic parameters. The mean activation energies obtained from the Kissinger, Kissinger-Akahira-Sunose, Ozawa-Flynn-Wall, and Friedman model are 107.583 kJ mol−1, 138.78 kJ mol−1,145.36 kJ mol−1, and 157.21 kJ mol−1 respectively. The maximum exergy efficiency for pyro-gas was 54.92%, with a particle size of < 0.5 mm at 600 °C. The present study shows that hazardous material like Prosopis juliflora can be converted into energy-dense fuel, thereby paving way for mitigation of the toxic weed. [Figure not available: see fulltext.] © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.