<p>Eucalyptus wood sawdust stands out as a promising bioenergy feedstock, owing to its rapid growth renewable nature. This work provides a comprehensive analysis of the thermal degradation and kinetic modeling of eucalyptus sawdust in an oxidizing atmosphere to optimize its combustion efficiency across a wide range of heating rates. High volatile (75.64%) and low ash (4.98%) content indicated good combustion properties, while the higher heating value of 17.03&#xa0;MJ kg^-1 underscores its high energy potential. The crystallinity index of 35% indicated a moderate presence of both crystalline and amorphous phases that influence biomass reactivity. Thermal decomposition occurred in three stages: moisture loss, active devolatilization of hemicellulose and cellulose, and gradual lignin breakdown and char formation. Kinetic modeling using iso-conversional methods resulted in an average activation energy around 125&#xa0;kJ mol^-1 across conversion levels (<i>α</i> = 0.2–0.7), showing a shift from reaction-controlled to diffusion-limited mechanisms. It is observed that first-order and diffusion mechanisms are dominant at lower heating rates (10–25&#xa0;°C min^-1), whereas higher rates (50–100&#xa0;°C min^-1) led to altered pathways due to thermal lag and secondary reactions. Gibbs free energy values between 172.78 and 176.56&#xa0;kJ mol^-1 indicated reaction spontaneity. Enthalpy remained stable (118–135&#xa0;kJ mol^-1) during early decomposition but declined at higher conversions. Entropy decreased, reflecting increased molecular order, while the energy barrier increased from 4.60 to 6.02&#xa0;kJ mol^-1 in later stages. By bridging gaps in EWS analysis at high heating rates, this work contributes to the development of optimized combustion or gasification strategies and supports the broader valorization of biomass for energy and environmental applications.</p> Graphical abstract <p></p>