Zinc titanate (ZnTiO3) phosphors containing Er3+/Yb3+ as active ions have been synthesized by using the solid state reaction method. The structural, surface morphology and optical properties of the Er3+/Yb3+ ZnTiO3 phosphors have been studied by X-ray diffraction (XRD), FE-SEM, EDX, Fourier Transform Infrared (FTIR), Raman analysis. The quantum computational program has been employed to investigate the FTIR spectra of geometrically optimized structure. The molecular orbital (MO) energy level diagrams for the electron spin states at the transition wave numbers have been reported. The transition states have been evaluated with time-dependent density functional theory (TDDFT) by using hybrid functional B3LYP. Photoluminescence study of the developed phosphors has been performed upon excitation at 426 nm and 980 nm from Xenon arc lamp and diode laser respectively. On introducing the Yb3+, the upconversion (UC) emission intensity of the green and red bands of the Er3+: ZnTiO3 phosphors have been enhanced about ∼ 52 and ∼ 132 times respectively. The temperature sensing study of the Er3+/Yb3+: ZnTiO3 phosphors upon 980 nm excitation up to 528 K temperature by using the green UC emission bands have been demonstrated.