The main purpose of this research is to explore the thermo-kinetics of the combustion process involving palm oil decanter cake (PODC) and alum sludge (AS) for bioenergy production. Thermogravimetric analysis (TGA) was utilized for the investigation and analyzing of the combustion characteristics. Coats-Redfern methods was applied to estimate the activation energy (Ea) and pre-exponential factor (lnA) using twelve reaction mechanisms. TGA curve revealed that unlike PODC, AS and blends exhibit two degradation ranges. The mass loss of PODC/AS co-combustion reduced with AS addition. Kinetic study revealed that for range I, 50PODC+50AS has the best reaction rate with models P3 and P4. Ea and lnA for P3 and P4 model are (13.52 kJ/mol and 7.19 min�1) and (11.13 kJ/mol and 6.57 min�1) respectively. �H, �G, �S for P3 and P4 models are (8.4 kJ/mol, 131.15 kJ/mol, �0.2 kJ/mol.K) and (6.02 kJ/mol, 131.96 kJ/mol, �0.21 kJ/mol.K) respectively. For range II, 50PODC+50AS has the best reaction rate with model A3. The Ea and lnA for A3 model are 41.40 kJ/mol and 12.36 min�1 respectively. �H, �G, and �S for A3 model are 35.16 kJ/mol, 153.84 kJ/mol, and 0.16 kJ/mol.K respectively. Overall, 50PODC+50AS demonstrated the highest reaction rate, suggesting its superior suitability for bioenergy production. © 2023 Elsevier B.V.