In this study, Ta wires 0.5 mm in diameter were carburized for 10-200 min at 2500°C in H2-0.5-3% CH4, 30 Torr, during which time the electric resistance and elongation of the filament were measured. After carburization, bending tests and S.E.M. observations were performed. Carburization proceeds in the sequence of Ta, Ta2C and TaC, forming concentric circular carbide layers in cross-section. Filament bending strength initially decreases to minima of 2-20 kgf/mm2 at about 20-60 min. However, it recovers up to 30-60 kgf/mm2 with further carburization. Filament embrittlement can thus be overcome through full carburization. Carburization time at the minimum strength, tb, roughly corresponds to the time at which the Ta2C layer disappears from the filament cross-section. Complete carburization results in filament expansion of about 5-8%. Electric resistance initially increases to a maximum at about 10-20 min, 2-3 times of which is roughly equal to tb. © 1998 Elsevier Science S.A.