► The concentration of TBH was reduced by 90% following electrolysis with BDD/Ti. ► Electrolysis with BDD/Ti electrodes led to the removal of 80% of total organic carbon. ► The reduction and formation of the byproducts of TBH could be monitored by HPLC. ► Ion chromatography confirmed that the electrochemical breakdown of TBH with BDD/Ti. ► The least doped BDD was the more efficient. The thiadiazolylurea derivative tebuthiuron (TBH) is commonly used as an herbicide even though it is highly toxic to humans. While various processes have been proposed for the removal of organic contaminants of this type from wastewater, electrochemical degradation has shown particular promise. The aim of the present study was to investigate the electrochemical degradation of TBH using anodes comprising boron-doped (5000 and 30000ppm) diamond (BDD) films deposited onto Ti substrates operated at current densities in the range 10–200mAcm−2. Both anodes removed TBH following a similar pseudo first-order reaction kinetics with kapp close to 3.2×10−2min−1. The maximum mineralization efficiency obtained was 80%. High-pressure liquid chromatography with UV–VIS detection established that both anodes degraded TBH via similar intermediates. Ion chromatography revealed that increasing concentrations of nitrate ions (up to 0.9ppm) were formed with increasing current density, while the formation of nitrite ions was observed with both anodes at current densities ⩾150mAcm−2. The BDD film prepared at the lower doping level (5000ppm) was more efficient in degrading TBH than its more highly doped counterpart. This unexpected finding may be explained in terms of the quantity of impurities incorporated into the diamond lattice during chemical vapor deposition.