Comparative work of erbium doped vanadium pentoxide and titanium dioxide thin films were carried out via sol gel technique by dissolving erbium (III) nitrate pentahydrate in vanadium (V) oxoisopropoxide and titanium (IV) isopropoxide. Fourier Transform IR and thermogravimetric/differential thermal measurements were performed to find out erbium substitution. UV-Vis. spectroscopy indicated a blue shift upon Er doping in V2O5 film due to the softening of V=O bond. The similar behavior was expected in TiO2 film and the prediction shall be shown only if annealing of the film above 600 degrees C, resulting oxygen deficiency in anatase TiO2 while Ti deficiency in rutile TiO2 film. Due to such impact of erbium on structure, granule size of the films, determined by AFM, increased yielding more space for intercalation of ion in host materials and monitored through cyclic voltammetry measurements.