Anodic　oxidation　of　catechols　1a-e　in　the　presence　of　5-methyl-2-mercapto-1,3,4-thiadiazole　2　has　been　studied　in　acetate　buffer　solution　by　cyclic　voltammetry　and　controlled-potential　electrolysis　techniques.　The　effects　of　various　electrolytic　conditions　(amount　of　passed　charge,　anodic　materials,　pH　of　the　electrolytic　Solution,　applied　potential,　and　concentration　of　substrates)　oil　the　yield　have　also　been　investigated.　The　results　showed　that　the　position　of　the　initial　substituent　of　the　starting　catechol　derivatives　dominated　the　formation　of　monothiadiazol-2-ylthio-substituted　or/and　dithiadiazol-2-ylthio-substituted　products.　For　4-substituted　catechols　1a-b,　monothiadiazol-2-ylthio-substituted　products　(3a-b)　were　exclusively　produced　in　high　to　excellent　yields.　However,　in　the　cases　of　catechol　itself(1c)　and　3-substituted　catechols　(1d-e),　both　monothiadiazol-2-yl-substituted　(3c-e　and　5d-e)　and　dithiadiazol-2-ylthio-substituted　products　(4c-e)　were　isolated.　in　addition,　the　nature　of　the　initial　substituent　of　the　starting　3-substituted　catechols　(1d　and　1e)　affected　the　relative　ratio　of　the　two　monothiadiazol-2-ylthio-substituted　isomers　(3d-e　vs　5d-e).　(C)　2009　Elsevier　Ltd.　All　rights　reserved.