Celtis mildbraedii sawdust (CMS) from Ghana was characterised to investigate its suitability with polyethylene terephthalate (PET) for syngas production via co-pyrolysis. The physical and chemical properties assessed include proximate and ultimate compositions, pH value, higher heating value (HHV), and lignocellulosic composition. Also, the thermal behaviour at different heating rates (5, 10, and 20 K/min) and qualitative prediction of organic compounds of CMS were examined using thermogravimetric analysis (TG/DTG) and NIR spectroscopy techniques, respectively. Results of proximate analysis (moisture = 17.15±0.0 wt.%, ash = 1.13±0.4 wt.%, volatile matter = 68.39±0.4 wt.%, fixed carbon = 13.33±0.8 wt.%); ultimate analysis (C = 48.51 wt.%, H = 6.66 wt.%, N = 0.51 wt.%, S = 0.02 wt.%, O = 44.30 wt.%); pH values (cold phase = 7.60, hot phase = 6.30); HHV (15.37 – 18.03 MJ/kg); and lignocellulosic composition (extractives = 13.80±0.57 wt.%, hemicellulose = 21.95±3.89 wt.%, lignin = 17.35±0.35 wt.%, cellulose = 46.90±2.97 wt.%) were obtained. The maximum mass loss was 83.48% at 289.8 °C at 5 K/min. It was concluded that CMS is a highly potential biomass resource for syngas production with an empirical formula of CH_1.64O_0.69N_0.009S_0.0001.