This work focuses on a comprehensive investigation of structure-activity relationships for a diesel engine soot sample (Corning) and 10 commercially available carbon black samples Particle sizes were determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Specific surface area was determined by nitrogen sorption. studies, While the Microstructure was investigated by X-ray diffraction (XRD) peak profile analysis, Raman spectroscopy, and TEM. Oxidation activity of these samples was studied using thermogravimetric analysis (TGA) under an Oxidative (10% O-2) environment consistent with the typical oxygen levels in the diesel engine, exhaust. Various. structural parameters, such as the average particle size, specific surface area, degree of organization, and average crystallite stacking height, were correlated with the TGA oxidation activity data. In general, samples with low particle size, high surface area, highly amorphous nature (low degree of organization), and low crystallite stacking height showed high oxidation activity. A second diesel engine soot sample. (Corning), which was collected at different operating conditions, was used to Validate the obtained structure-activity correlations Overall, our rigorous analysis for a large number of samples with multiple techniques indicated Unique and novel correlations/trends between soot structure and reactivity.