A novel tridentate thiosemicarbazide-type ligand class with an SNS donor set, H2L1, was prepared by reactions of N-[N',N'-dialkylamino(thiocarbonyl)]benzimidoyl chlorides with thiosemicarbazides. H2L1 ligands readily react with (NBu4)[TcOCl4] in MeOH under the formation of red oxotechnetium(V) complexes of composition [TcOCl(L-1)]. The monomeric, five-coordinate compounds are air-stable and bind (L-1)(2-) tridentate in the equatorial coordination sphere. The compounds represent the first examples of oxotechnetium(V) complexes with NS chelate-bonded thiosemicarbazones.