Composites of cobalt ferrite nanorods in a polyaniline matrix have been synthesized and characterized by electron microscopy observation, X‐ray diffraction, infrared spectroscopy, thermogravimetric analysis, electrical conductivity, and DC magnetization measurements. The composites were prepared using dodecylbenzenesulphonic acid both as a particle protector and as acid media. In the magnetic experiments, hysteresis loops were observed, revealing ferromagnetism for both particles and composites. The results indicate that the magnetic properties of the particles were preserved in the composites, and on the other hand, the conductivity was almost independent on the polymer/particle ratio. These composites are new materials that show easily tunable magnetic properties, and are expected to be candidates for applications such as microwave shields. POLYM. ENG. SCI., 60:597–606, 2020. © 2020 Society of Plastics Engineers