Abstract <p>Magnetoplumbite-type (M-type) hexagonal barium ferrite samples were prepared by solid-state method. The effects of Ca–Ba ratio and calcination temperature on structural and magnetic properties were investigated through tests and from results it was found that the variation in ratio of Ca–Ba and temperature have an important effect on structure and magnetic properties of recently prepared samples of M-type hexaferrites. The XRD patterns confirmed the presence of single-phase up to <i>x</i> = 0.75. However, an undesired secondary phase appears in the form of α-Fe₂O₃ for compositions near the upper Ca substitutions. Although in Ba_{0.75 – <i>x</i>}Ca_<i>x</i>La_0.30Fe₁₂Co_0.25Ti_0.15O₁₉, the theoretical substitution limit for Ca is <i>x</i> = 0.75 but to examine the solubility limit and resulting phase instability, higher Ca content compositions were deliberately synthesized and included. Lattice constants (<i>c</i> and <i>a</i>) as well as the ratio <i>c</i>/<i>a</i> vary with the variation in Ca–Ba ratio content (<i>x</i>) and these variations were discussed. FE-SEM micrographs exhibit platelet-like morphology which is a characteristic of M-Type hexaferrites and consistent with the results determined by XRD. Variations in saturation magnetization (<i>M</i>_s), remanent magnetization (<i>M</i>_r) and coercivity (<i>H</i>_c) with calcination temperature were also discussed. It was observed that <i>M</i>_s and <i>M</i>_r initially decreased with increasing calcination temperature and then increased at higher temperatures, while coercivity showed a continuous increase with temperature.</p>