In the present work the solidification of various Mo-Ti-B alloys was studied. The alloy compositions were chosen in the direct vicinity of a U-type invariant reaction in relation to the published Mo-rich corner of the Mo-Ti-B liquidus projection. The aim of this study was to understand the solidification path of as-cast Mo-Ti-B alloys and to derive specific knowledge on their peritectic microstructure evolution. In addition to experiments in an arc-melter, zone melting was used to allow slow cooling of a selected alloy composition. Using the achieved experimental data of the alloys investigated, DFT-calculations were carried out to study the influence of Ti on phase formation and stability, their lattice parameters, and mechanical properties.