The corrosion behavior of tantalum (Ta) and niobium (Nb) in hydrobromic acid solutions has been studied with respect to their surface states and hydrizing by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), a hydrogen determinator, and x-ray diffraction (XRD). The test specimens were immersed in a 47 wt% HBr solution bubbled with hydrogen and in another that contained 0.05 mol/dm3 of bromine at 25 and 100°C for 15, 30, and 45 days. On Ta under every condition and Nb at 25°C, the surface films consisting of their pentoxides thickened with increasing immersion time and exhibited no significant changes in appearance or hydrogen content. However, fine pits less than 5 µm in diameter were formed on Nb specimens in both the solutions at 100°C at the early stage of immersion. In the solution with hydrogen, the pitting extended over the specimen surfaces with increasing immersion time, and developed into general corrosion after 45 days, while the progress of the pitting was terminated in 15 days in the solution with bromine. Furthermore, only with Nb in the solution with hydrogen at 100°C the surface film did not thicken or absorb hydrogen. It has been found that Ta is passivated and stable in hydrobromic acid solutions below 100°C, and that Nb is corrosion-resistant to HBr solutions with oxidizing agents, but it actively corrodes with hydrogen absorption in HBr solutions under reducing conditions at high temperatures.