High resolution infrared emission spectra of beryllium monohydride and monodeuteride have been recorded. The molecules were generated in a furnace-discharge source, at 1500 °C and 333 mA discharge current, with beryllium metal and a mixture of helium and hydrogen or deuterium gases. Approximately 160 BeH lines and 167 BeD lines for the vibrational bands v=1→0 to v=4→3 were observed in the spectra and spectroscopic constants were determined. The Dunham constants (Yl,m) and Born-Oppenheimer breakdown constants were obtained in a combined fit of the BeH and BeD data. The equilibrium rotational constants (Be) for BeH and BeD were found to be 10.319 59(3) cm-1 and 5.688 29(2) cm-1, respectively, while the equilibrium vibrational constants (ωe) are 2061.416(3) and 1529.956(3) cm-1. The equilibrium distance (Re) was determined to be 1.342 436(2) Å for BeH.