High resolution infrared emission spectra of beryllium dihydride and dideuteride have been recorded with a Fourier transform spectrometer. The molecules were generated in a discharge-furnace source, at 1500 degreesC and 333 mA discharge current, with beryllium metal and a mixture of helium and hydrogen or deuterium gases. The antisymmetric stretching modes (nu(3)) of BeH2 and BeD2, as well as several hot bands involving nu(1), nu(2), and nu(3), were rotationally analyzed and spectroscopic constants were determined. The equilibrium rotational constant (B-e) of BeH2 was found to be 4.753 66(2) cm-1, and the equilibrium bond distance (R-e) of 1.326 407(3) A was determined for BeH2. (C) 2003 American Institute of Physics.