  We report on the superconductivity in ternary transition metal tellurides
Ta2Pd3Te5 and Nb2Pd3Te5, which have a one-dimensional crystal structure.
Single-crystalline and polycrystalline samples of Ta2Pd3Te5 show nonmetallic
electron conduction, while Ti or W doping results in metallic behavior with a
bulk superconducting transition at 2-4 K. In contrast, the polycrystalline
samples of Nb2Pd3Te5, which are found to be isostructural to Ta2Pd3Te5, show a
bulk superconducting transition at 3.3 K. The crystal structure and physical
properties of Ta2Pd3Te5 and Nb2Pd3Te5 are also discussed in comparison with a
candidate excitonic insulator Ta2NiSe5.
