  Hydrogen dynamics in the nanoscale region of VO$_{2}$ was investigated by
muon spin rotation/relaxation ($\mu $SR) technique. Positively charged muon
acts as a light radioisotope of proton and can be used as a probe to explore
the inside of materials from an atomic perspective. By analyzing the muon
hopping rate and the spatial distribution of the $^{51}$V nuclear magnetic
moments, we have identified two types of diffusion paths in VO$_{2}$ (via
oxygen-muon bonds or defects) and the potential of a high diffusion coefficient
in the 10$^{-10}$ cm$^{2}$/s range at ambient temperature. Our results provide
valuable information for developing hydrogen-driven VO$_{2}$--related
electronic devices.
