The present work deals with the thermal behavior investigation of new biocomposite materials intended to be used for process engineering applications. Particular attention is given to the thermal degradation of such materials. Thermal characterization at different scales is performed using thermogravimetric analysis (TGA) and cone calorimeter experiments. The main purpose is to compare the thermal behavior of new bamboo-based and banana-based Green Biocomposites (GBCs). An intumescent fire retardant (IFR) coating, which is a mixture of APP and boric acid was applied on the GBC sample surface to study the flame retardancy. The GBC samples was first manufactured using a vacuum resin transfer molding. TGA results showed that bamboo-based (BM-GBC) and banana-based (Bn-GBC) materials exhibits similar thermal degradation pattern. While cone calorimeter experiments revealed that BM-GBC outperforms than Bn-GBC. The IFR coating improved the flame retardancy of both GBCs by reducing the heat release rate as well as a noticeable reduction in terms of smoke emission. Finally, to improve the thermal stability of Bn-GBC material, SiC powder is added as a filler. The IFR coating and SiC powder addition promotes considerably the thermal behavior of Bn-GBC materials.