Molybdenum oxides have attracted much interest due to their unique electronic properties. Here, we report a convenient and efficient method to synthesize centimeter-scale single crystal of MoO ribbons through an atmospheric pressure physical vapor deposition approach. Optical microscopy, atomic force microscopy, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction, and x-ray diffraction measurements reveal that the MoO ribbons grow along the MoO〈100〉 direction and the top surface is MoO(010) plane. Raman spectroscopy, x-ray photoelectron spectroscopy, and cross-sectional HRTEM results disclose that the surface of MoO ribbons can be transformed from MoO to MoO through H annealing treatment forming MoO/MoO heterostructure. We found that the conductance and ultraviolet photoresponsivity of the MoO ribbons can be improved by ∼11 and ∼5 orders of magnitude, respectively, after H annealing treatment, which will be helpful for the applications of MoO in the optoelectronic field.