Carbamazepine (CBZ), a widely detected pharmaceutical in wastewaters, cannot currently be treated by conventional activated sludge technologies, as it is highly resistant to biodegradation. In this study, the degradation kinetics and reaction mechanisms of CBZ by hydroxyl radical (OH) and sulfate radical (▪)–based advanced oxidation processes (AOPs) were investigated with a combined experimental/theoretical approach. We first measured the UV absorption spectrum of CBZ and compared it to the theoretical spectrum. The agreement of two spectra reveals an extended π–conjugation system on CBZ molecular structure. The second–order rate constants of OH and ▪ with CBZ, measured by competition kinetics method, were (4.63 ± 0.01) × 109 M−1 s−1 and (8.27 ± 0.01) × 108 M−1 s−1, respectively at pH 3. The energetics of the initial steps of CBZ reaction with OH and ▪ were also calculated by density functional theory (DFT) at SMD/M05–2X/6–311++G**//M05–2X/6–31 + G**level. Our results reveal that radical addition is the dominant pathway for both OH and ▪. Further, compared to the positive ΔGR0 value for the single electron transfer (SET) reaction pathway between CBZ and OH, the ΔGR0 value for SET reaction between CBZ and ▪ is negative, showing that this reaction route is thermodynamically favorable. Our results demonstrated the remarkable advantages of AOPs for the removal of refractory organic contaminants during wastewater treatment processes. The elucidation of the pathways for the reaction of OH and ▪ with CBZ are beneficial to predict byproducts formation and assess associated ecotoxicity, providing an evaluation mean for the feasibility of AOPs application. Display omitted •The k values of OH and ▪ with CBZ were 4.63 × 109 and 8.27 × 108 M−1 s−1.•DFT result showed energy barriers of ▪ reacting with CBZ was higher than OH.•Radical addition was the dominant pathway for both OH and ▪ reacting with CBZ.•Remarkable advantages of AOPs for removal of organic contaminants were exhibited. The k values of OH and ▪ reacting with CBZ were measured to be 4.63 × 109 and 8.27 × 108 M−1 s−1, respectively. Radical addition is dominant reaction pathway.