Ni(NO3)3.6H2O has been thermally decomposed to synthesize NiOx (0 < x < 1) and a modified citrate-nitrate route has been employed for LaNiO3-δ synthesis. These metal oxides have been characterized by XRD, SEM, TEM, XPS and UV–vis spectroscopy for the determination of their crystal structures, structural morphologies, oxidation states and optical band gaps. The devices, made of nanocrystalline-composites or nanocomposites, have been fabricated on gold coated soda lime glasses, where the device based on NiOx has been found applicable for UV photo-conducting and LaNiO3-δ has been recognized as a potential IR photo-conducting sensors. Their respective current amplifications have been recorded 8 and 2.2 times more than the dark current at 2 V of DC bias. The UV sensor has been explained by direct band gap semiconducting nature of NiOx and IR sensitivity of LaNiO3-δ was explained in terms oxygen deficiency induced band gap opening. © 2018 Elsevier Ltd