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Neonicotinoids pesticides were introduced to the market in the 1990s to control various pests. Its accumulation in the environment supposes a severe problem that can affect human health. This study investigates the electrochemical degradation of four common neonicotinoid pesticides; thiamethoxam (TMX), imidacloprid (ICP), acetamiprid (ACP) and thiacloprid (TCP), in different natural surface waters by a boron-doped diamond anode (BDD). The most influencing variable was the current density (j), and to a lesser extent, the supporting electrolyte concentration (C e). In optimal conditions (j = 34.14 mA cm−2 and C e = 10.00 mM, using Na 2 SO 4 as electrolyte) pesticide removals for TMX, ICP, ACP and TCP were 97.2, 96.9, 87.8 and 98.2 %, respectively. The obtained results with different support electrolytes (Na 2 SO 4 , NaCl, NaNO 3 and HK 2 PO 4) suggest that sulphate electrolyte was the optimum for TMX, ICP and ACP. However, for TCP, a total removal was achieved in less than 10 min using NaCl. It was also verified that the initial pH of the solution did not significantly influence the process in the range 3–9. All these results were rationalized in this paper. Finally, to evaluate the matrix influence, some experiments were carried out in different natural surface water matrices (river, reservoir and two different WWTP effluents). The factors influencing the process were the conductivity of the solution and the organic matter content. It was noticeable that the specific energy consumption (SEC) reduced by approximately 15 % for river water and WWTP effluent. High mineralization rates were obtained for all water matrices, with TOC removals ranging between 60 and 80 %. [Display omitted] • BDD electrochemical oxidation of neonicotinoid pesticides in natural surface waters: river, reservoir and WWTP effluents. • The most influencing operating variable was the current density and, to a lesser extent, support electrolyte concentration. • The most influential environmental factors in natural surface waters matrices were conductivity and organic matter content. • Specific energy consumption was reduced by approximately 15 % for river water and WWTP effluents compared to ultrapure water. [ABSTRACT FROM AUTHOR]