The concept of circular economy is aiming at promoting innovative use of wastes, residues, or byproducts into marketable chemicals and intermediates, while enhancing process economics and environmental sustainability. Within biorefineries, the focus has now shifted toward “humins”, polymeric condensation byproducts far less investigated than lignins. Humins are produced in many biobased value chains that start from polysaccharides pretreatment, targeting access to C6 and C5 sugars and further conversion to furanics- or levulinics-based platform chemicals. They are complex and versatile substrates, and combustible because of their organic nature. A first insight on safety issues of humins is therefore proposed in this paper, considering the growing interest in humins as new biobased feedstocks for various applications. The current study provides characterization details necessary to establish safety information on a global context. This first attempt has brought in preliminary safety data mainly focusing on thermal and fire hazards of humins, to ensure safe storage, handling, transportation, and processing. The obtained results show that overall fire risk of humins so far is similar to that of the conventional cellulosic fuels such as woody materials. Further consolidation of safety information shall be done with a scenario-based risk assessment approach for conditioning safe use of humins in further innovative applications.