[en] Thermoreflectance studies of bulk samples of V, Nb, Ta, and α-phase TaH/sub x/ are reported and the results interpreted in terms of recent band calculations. The first interband transition is identified as a transition involving the Σ band at E/sub F/. An M₃ critical-point transition is attributed to states at N. Significant changes induced by interstitial hydrogen in solid solution α-TaH/sub x/ are observed and interpreted as due to hybridization and lowering of the N/sup prime/₁ eigenenergy