Little is known about the characteristics of hydrogen states in thin films of SnO₂ and Nb doped SnO₂ (NTO) and its influence on the electrical properties in these materials, which are promising candidates for metal-oxide supports in polymer electrolyte fuel cells. Here, we used low-energy muon spin rotation/relaxation (LE-µSR) to study hydrogen-like muonium (Mu) states between 5 K and 300 K in undoped and Nb doped SnO₂ films with Nb doping levels of 0.1% and 2%, respectively. The films were prepared by reactive DC magnetron sputtering on undoped Si substrates. Film thicknesses varied between 75 nm and 200 nm, and muons were implanted close to the surface at a mean depth of 10 nm, in the center of the films, and in some cases close to the NTO/Si interface. Our results of transverse-field and longitudinal-field µSR show striking similarities to recent bulk µSR measurements on various zirconia systems [Vieira et al., Phys. Rev. B 94, 115207 (2016)]. This suggests that in the NTO systems the same Mu configurations exist which are the interstitial site with a deep, isotropic atomic Mu state, and, as the dominant fraction, the oxygen bound configuration with polaronic character.