The reaction of three chloronicotinoid insecticides, namely Imidacloprid (IMD), Thiacloprid (THIA) and Acetamiprid (ACT), with carbonate radicals (CO₃⁻) was investigated. The second order rate constants (4 ± 1) × 10⁶, (2.8 ± 0.5) × 10⁵, and (1.5 ± 1) × 10⁵ M⁻¹ s⁻¹ were determined for IMD, THIA and ACT, respectively. The absorption spectra of the organic intermediates formed after CO₃⁻ attack to IMD is in line with those reported for α-aminoalkyl radicals. A reaction mechanism involving an initial charge transfer from the amidine nitrogen of the insecticides to CO₃⁻ is proposed and further supported by the identified reaction products. The pyridine moiety of the insecticides remains unaffected until nicotinic acid is formed. CO₃⁻ radical reactivity towards IMD, ACT, and THIA is low compared to that of HO^• radicals, excited triplet states, and ¹O₂, and is therefore little effective in depleting neonicotinoid insecticides.