The reaction of tetrabutylammonium pertechnetate with bis(trimethylsilyl) sulfide in solution was studied by UV-Visible spectroscopy and mass spectrometry. Experimental results and density functional calculations provide the first evidence for the formation of a TcO3S− precursor. Larger scale synthesis afforded a solid that was characterized by EDX and XANES spectroscopy. XANES showed the presence of technetium in tetravalent state. EDX indicated the solid contained technetium, sulfur and oxygen.