Because of the unexpectedness, the chemical involved in a hazardous incident is often not known immediately and can hardly be derived directly from the information at the scene. This situation is especially true for transportation incidents. As the result, hazardous chemical incidents can generate additional property damage and human injuries. Therefore, identification of the hazardous chemical should be an important step, to be made before any subsequent decisions. The present paper proposes a scheme for chemical identification in transportation hazards. In the scheme, all possible kinds of information from the scene are considered, including general information, shipment documents, observable properties of the hazard and the chemical, and clinical manifestations. With a practical example, it is shown to be possible, in a successive and interactive manner, to establish a computer module for such an identification.