Ab initio basis-set-limit total atomization energies Sigma D-0 have been calculated for the first-row hydrides and hydride radicals. Agreement to within about 0.1 kcal/mol with experiment is found for those species where experimental data of this accuracy are available. For the other species, the following new or revised Sigma D-0 values are proposed: BeH 47.7, BeH2 140.9, BH 81.5, BH2 160.8, BH3 264.6, CH2 179.9, NH 78.4, NH2 170.7, and OH 101.7 kcal/mol. These values are expected to be correct to 0.2 kcal/mol or better. (C) 1997 Published by Elsevier Science B.V.