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Abstract: Ferrimagnetic glass–ceramics are potential candidates for magnetic induction hyperthermia, which is one form of inducing deep-regional hyperthermia, by using a magnetic field. The aim of this work was to analyse the influence of the amount of crystallised magnetite on the magnetic properties of glass–ceramic samples. Thus, two different ferrimagnetic glass–ceramics with the composition of the system Na2O–CaO–SiO2–P2O5–FeO–Fe2O3 were prepared by melting at 1500°C for 30min of the coprecipitation-derived starting products. The X-ray diffraction patterns show the presence of nanometric magnetite crystals in a glassy matrix after cooling from melting temperature. The estimated amount of crystallised magnetite varies between 20 and 45wt.%, as a function of the chemical composition. The morphology of the crystals was studied by scanning electron micrography and transmission electron micrography. Glass transition temperature and thermal stability were investigated by differential thermal analysis. Magnetic hysteresis cycles were analysed using a vibrating sample magnetometer with a maximum applied field of 17kOe, at room temperature, in quasi-static conditions. Calorimetric measurements were carried out using a magnetic induction furnace. The power losses estimated from calorimetric measurements under a magnetic field of 40kA/m and 440kHz are 65W/g for the glass–ceramic with lower iron oxides content and 25W/g for the glass–ceramic with higher iron oxide content. [Copyright &y& Elsevier]