Hybrid composite specimens out of basalt and flax fibers reinforced with a cyanate-ester and epoxy resin combination were subjected to cone evaluation in a cone calorimeter. The increase of the BF layers within the hybrid architectures significantly decrease the pHRR and CO/CO₂ released content but not the residues at the end of the combustion process. On the other hand, flax fiber reinforced composites ignite earlier, release a relatively high amount of heat and leaves reduces residues at the end of the combustion process. Further studies on fire-retardant additives deployment within these hybrid structures are expected to boost the flammability outcomes.