Structure-property relationship in BaTiO2 (BT)-based dielectrics for multi-layer ceramic capacitors with nickel internal electrode was investigated using samples having various HoO3/2 concentrations by measuring temperature characteristics of capacitance, voltage-current characteristics, lifetime at highly accelerated life test, high-resolution analytical electron microscope, and frequency response at elevated temperature and ultra-low frequency. It was concluded that the addition of Ho affected the shell and grain boundary characteristics. Incorporation of Ho into BT perovskite lattice and the change in GB characteristics, along with the doped concentration of HoO3/2 were discussed to better understand the role of doped Ho2O3.