The presented publication deals with the complex investigation of fire risk of selected most commonly used natural and synthetic polymers and combustible liquids. The publication presents a newly developed method that allows complex assessment of fire risk of solid and liquid combustible materials in such a way that the obtained data can be applicable in all areas related to fire safety. The described method quantifies material susceptibility to fire initiation and subsequent fire propagation, and its impact on lives and health of people, environment, and assets. The publication is primarily devoted to scientists and researchers, but it can also be used by fire protection engineers (specialists), fire investigators, and designers of technical and technological devices.