Perovskite-type oxides La1-xBixNi0.5Ti0.5O3 (x = 0.0, 0.2) were prepared by the sol–gel method employing the citric acid route and sintered at 820° C. The structural behavior analyzed by X-ray diffraction proved that all the samples have the same crystallographic structure (space group Pnma). The volume of the elemental lattice decreases with the rate of Bismuth substitution. Transmission electron microscopy (TEM) verified the nanosized grains. The FTIR spectra confirmed the formation of the orthorhombic perovskite structure. UV–Visible spectroscopy and photoluminescence were also applied to study the samples. The parameters of real and imaginary part of dielectric function (ε′ and ε″) and dielectric loss tangent (tg(δ)) show a strong frequency dependence. Those dependences explain a dispersive behavior at low frequencies and are outlined on the basis of the Maxwell–Wagner model and Koop theory. The compounds have very high dielectric constant values (ε′ ≈ 103) that are useful in electronic devices. Electric modulus formalism was employed to investigate the relaxation dynamics of charge carriers. Moreover, a non-Debye type of relaxation was verified in our samples. The activation energy is specified from the analysis of the imaginary part of the electric modulus. Graphic abstract: [Figure not available: see fulltext.].