Polycrystalline ceramic samples of calcium (Ca2+)-doped barium titanium silicate mineral (fresnoite) of general formula Ba2−XCaXTiSi2O8, have been prepared by a standard solid-state reaction method using high-purity oxides and carbonates. The formation of the single-phase compound and its structural parameters were investigated by X-ray diffraction (XRD) followed by Rietveld refinement and scanning electron microscopic techniques. A better agreement between the observed and calculated XRD patterns was obtained by performing the Rietveld refinement with a structural model using the noncentrosymmetric space group P4bm. A better agreement between observed and calculated d-values also show that the lattice parameters calculated using the Rietveld refinement analysis are better than that of the earlier report so far. The activation energies of the compounds were calculated by measuring their dc electrical conductivities. The activation energy obtained for the pure compound is very high (4.74 eV), which decreases with the increase of doping concentrations. The frequency and temperature-dependent dielectric behavior of the compound has been studied. The results are discussed in detail.