Abstract A high level of ab initio and B3LYP hybrid density functional studies were performed with the target being to determine both the reliability of these two methods for computing energetic properties of small silicon–hydrogen compounds, and the accuracy of the currently available thermodynamic properties of these compounds. These energies are Si–H and Si–Si bond dissociation energies, atomization energies, and heats of formation. The hybrid B3LYP ab initio computational study was performed in combination with five different basis sets. Currently available experimental energies for these compounds have a large experimental error, but with the CBSQ(0 K) energies it was possible to narrow these experimental values. In general, the B3LYP hybrid DFT method with a large basis set computes energies that are slightly below the CBSQ values.