The bond dissociation enthalpies in n-silanes and n-germanes have been studied with the G2MP2 and G3B3 computational methods. The results have been compared with those of the corresponding n-alkanes. The differences observed in the three families of compounds have been rationalized using the calculated hyperpolarization effect in each family. In addition, the conformational profiles of X2H6 molecules, X = C, Si, and Ge, have been compared. (c) 2006 Elsevier B.V. All rights reserved.