Chemiluminescence spectra of electronically excited BH/BD products from the reaction of B(4p 2 P) with H 2 and D 2 have been observed and analyzed. The boron atom reagent was formed by 266-nm multiphoton dissociation of BBr 3 , and the 4p 2 P level was prepared by sequential laser-induced radiative transitions through the 3s 2 S level. Chemiluminescence rate constants for production of the A 1 Π, b 3 Σ - , and C' 1 Δ electronic states were determined by comparing the intensities of the product chemiluminescence and the 4p 2 P→3s 2 S radiative decay of the atomic reagent