Shape-memory polymer–magnetite (Fe₃O₄) composite samples were prepared by extrusion compounding and injection molding. Thermal diffusivity, conductivity and specific heat capacity were measured from 290 K to 340 K. Increasing filler fraction decreases specific heat capacity and increases thermal diffusivity. Experimental results show a good agreement with Agari–Uno and Hashin–Shtrikman models but not with Bruggeman model. The interconnectivity of the particles is very poor. Agari–Uno model leads to a high influence of polymer on thermal properties. Below 350 K mainly the polymer and above 350 K mainly the Fe₃O₄ influences specific heat capacity that shows drastic changes around 310 K (recovery temperature) and 357 K.