Epidemiological studies have shown that soot particles can cause pulmonary disease, cardiovascular damage and mortality. New findings show soot may be accelerating melting of sea ice and snow and changing atmospheric temperatures. Therein identification of emission sources is of increasing importance. Combustion produced soot is a highly variable material. Physically the nanostructure can range from amorphous to graphitic to fullerenic. Chemically nearly any element could be included, though the surface functional groups are predominantly oxygen-based. Presented here are image analysis results of HRTEM images of the physical nanostructure and XPS analysis of the chemical composition of soots collected from plant, institutional and residential scale oil-fired boilers, diesel engine, gas-turbine combustor (jet) and a wildfire. Physically soots from these emission source classes may be differentiated based on carbon lamella length, mean separation and tortuosity. Chemically these soots may also be distinguished by elemental composition, surface (oxygen) functional groups and carbon bonding.