The results of the influence of thermal and chemical treatments on the surface morphology of (110) NdGaO₃ substrates are described in this paper. The treated surfaces were analysed by Atomic Force Microscopy (AFM), in air, and by in-situ high pressure Reflection High Energy Electron Diffraction (RHEED). The thermal treatment of substrates resulted in a NdO_1+x single terminated surface, while a surface with GaO_2-x terminating layer and atomically flat terraces without etch pits could be obtained by chemical etching in a HF + NH₄F + H₂O solution, followed by an annealing step at high temperatures (900-1000^oC) in air or in oxygen flow, for surface recrystalization.