[en] The citrate-nitrate gel combustion route was used to prepare SrFe₁₂O₁₉(s), BaFe₁₂O₁₉(s) and PbFe₁₂O₁₉(s). The compounds were characterized by Rietveld profile analysis of the X-ray powder diffraction data. The thermal expansion coefficients of MFe₁₂O₁₉ (M = Sr, Ba and Pb) were determined using high temperature powder X-ray diffraction data. The lattice parameters of these compounds were fitted into polynomial expressions as a function of temperature. Melting points of MFe₁₂O₁₉ (M = Sr, Ba and Pb) were determined using high temperature calorimeter and the values are; 1632 K, 1611 K and 1538 K, respectively. Standard molar heat capacities of BaFe₁₂O₁₉(s) and PbFe₁₂O₁₉(s) were determined from 130 K to 850 K using a heat flux type differential scanning calorimeter (DSC) and heat capacity anomalies were observed at 725 K and 718 K, respectively. This heat capacity anomaly is due to the magnetic order-disorder transition from ferrimagnetic state to paramagnetic state