A knowledge of material safety properties is an essential requirement for the safe handling of unit operations. Incidents in plants can often be traced to an insufficient knowledge of the hazardous properties of combustible substances. Unforeseen violent reactions in which destructive energies or large amounts of hazardous materials were released have resulted. Safety properties provide information on the reaction behaviour of the substances and possible fire and explosion hazards, presupposing that they are determined carefully and applied properly. The paper provides definitions of the material safety properties and brief descriptions of their methods of determination, which should be standardized internationally if at all possible, and describes various evaluation criteria. The analysis distinguishes between dust layers and dust suspensions.