Potential energy surfaces (PES) of the experimentally elusive species HGaX and HXGa (X = O, S, Se) were studied by ab initio calculations. Molecular geometries of linear and bent conformers were otimized at HF and MP2 levels. Split-valence triple-zeta basis sets augmented by two sets of p polarization functions on hydrogens and two sets of d polarization functions on heavy atoms were used in our study. All stationary points on PESs were characterized by harmonic vibrational frequencies calculated at the HF and MP2 levels. Relative stability of the studied species and their thermodynamical stability toward dissociations into H + GaX and H+ + GaX(-) fragments were studied at the MP4(SDTQ) level of theory at the MP2 optimized geometries. Strongly bent HXGa conformers are the global minimum species, which is in contradiction to Walsh’s rules predicting linear structures for the 10-valence-electron HXY systems.