Ba1−xCaxTi1-yZryO3 materials have very high dielectric constant (up to 30,000) in the bulk form. In this paper, we are presenting the electrical and structural characteristics of undoped and 0.4% Mg-doped Ba0.96Ca0.04Ti0.84Zr0.16O3 (BCTZ) thin films on Pt/Ti/SiO2/Si substrates. The BCTZ films were deposited by spin on metal-organic decomposition method and annealed at a temperature 600-900°C in oxygen environment. The annealed thin films were characterized by X-ray diffraction. The electrical characteristics of the annealed thin films were analyzed by capacitance–voltage and current–voltage measurements. The as-annealed thin films were post- annealed in nitrogen and oxygen environments and the effect of post-annealing on their electrical characteristics were also presented in conjunction with 0.4% Mg doping effect of BCTZ thin films for possible high dielectric constant material applications.