Ab initio electronic structure calculations are reported for TiH2O and TiH3OH, the simplest prototypical molecules containing Ti=O and Ti-O bonds, respectively, with particular focus on the unimolecular decomposition mechanisms of TiH3OH and the isomerization of TiH2O. The equilibrium structures in the ground and lowest excited states and the potential energy surfaces for various unimolecular decomposition reactions are investigated, with the effects of electron correlation included. At the highest levels of theory (multiconfigurational wave functions augmented by second-order perturbation theory), singlet TiH2O is predicted to be the global minimum on its potential energy surface, and TiH3OH is predicted to be stable to unimolecular decomposition.