 This study aims to develop sustainable and low-cost thermal insulators from banana leaves polystyrene composites, BLPS, as a replacement for petrochemical materials that have negative environmental impacts. The BL powder was mixed with PS in different weight ratios, and thermal conductivity, electrical conductivity, SEM, XRD, FTIR, TGA, and DSC were carried out on the prepared composites. The results show low thermal conductivity, ranging from 0.0183 to 0.03168WM.K, with the least value recorded for BL, PS1, with high crystallinity and thermal stability. The findings suggest that banana leaves composite can be used as an eco-friendly and inexpensive thermal insulating material. This article was authored by Jihad Amohamed, Rehab K Mahmoud, Irene Esfahim, and others.