Summary: Ethylene-octene copolymer (EOC) modified polypropylene (PP) and polyoxymethylene (POM) were used as matrices for development of ZnO modified composites. EOC content in the composites was 10, 30 and 50 wt%, while ZnO content was 2 and 5 wt%. It was determined that addition of ZnO increased stiffness, strength and thermal resistance, as well as decreased coefficient of friction of the investigated composites. Somewhat greater increase of these characteristics was observed at 2 wt% of ZnO. Properties ZnO modified composites are also strongly affected by incompatibility of it ingredients, especially at higher EOC content.