Highly filled polymer-particle composites were compounded and afterwards processed by injection molding into samples for material characterization. Those composites can be applied in different fields of electronics. The polymer matrices used were polyamide (PA) and polyphenylensulphide (PPS). Furthermore, two types of ferrite micro particles (FMS 50 and FMS 150) were admixed to the polymer matrices in filler contents of 50 vol.-%, 60 vol.-% and 65 vol.-%. The powders were characterized by tri-modal particle size distributions with particle collectives at d10, d50 and d90. With increasing filler content, torque at kneading rotors and injection molding parameter e.g. injection pressure significantly increased. REM micrographs of the injection molded composite specimen show well distributed spherical micro particles. TGA was used to characterize the real filler content and the thermal stability of the composite. Thermal stability of the compound was verified up to 200°C. Neat polymers show slightly higher crystallinity and melt peak temperature compared to the composites. Defined cooling with 10 °C/min significantly increases the crystallinity and melt peak temperature of neat polyamide and composites compared to undefined cooling after injection molding. The storage modulus of polymers, however, also increases significantly by adding the investigated filler particles.