In this study, we report the thermophysical properties (at room temperature) and the morphology of a composite with a polyester resin matrix and magnetite filler powders (Fe₃O₄), conformed in three configurations: randomly dispersed particles, particles oriented parallel to a constant 300 mT magnetic field, and particles oriented perpendicular to a constant 300 mT magnetic field. Samples were formed by hand lay-up with weight percentages of 10, 20 and 30%, where the highest concentration corresponds to the resin. The thermophysical properties were determined using the KD2 Pro^® system, which uses the physical principle of linear transient heat flow, for which the dual sensor SH-1 was used. The morphology and microanalysis were studied using a scanning electron microscope (SEM, FEI Quanta 650 FEG). It was observed from the morphology that the magnetite particles are oriented in the direction of the magnetic field lines during the process of resin curing. It was also perceived that the values of the thermophysical properties found experimentally are within the limits (upper and lower) of Hashin and Shtrikman and that those values increase when the magnetite concentration increases in the sample. No significant difference was observed in the thermal properties because of the magnetic field applied.