The ever-growing emission of greenhouse gases has been a major contributor to climate change. Solutions include CO2 storage and utilisation. Moreover, scarcity of non-renewable resources has driven adoption of biocomposites. Therefore merging CO2 utilisation with biocomposites was investigated. Combinations of natural fibres and solutions were screened for their CO2 capture capacity, and chosen for optimisation of reaction pressure, temperature and time using the response surface method (RSM) to maximise CO2 capture. Thermogravimetric analysis (TGA) was used to carry out kinetic analysis of isothermal CO2 capture, using the optimised sorbents. Sorbents were also pyrolised and decomposition temperatures indicated presence of ammonium bicarbonate and carbonate, and sodium bicarbonate, which were also confirmed with FTIR and Scanning Electron Microscopy. Recycled LDPE was compounded with sorbents to make biocomposites, and the effect of sorbent loading and extruder die temperature on their physical properties was modelled with RSM. The densities, yield and ultimate strengths were higher at lower sorbent-loadings and die temperatures, whereas Young’s moduli were higher at higher sorbent-loadings and die temperatures. TGA of biocomposites showed single-step decomposition and the same temperature of maximum degradation rate. Kinetic analysis revealed that some biocomposites increased the thermal stability of LDPE.