In this study, electrostatic powder coating waste in their appropriate hydrolyzed thermoset structure were mixed with various polyolefins in different ratios and the dependence of the flow indexes and densities of the polyolefins in the melt flow on the powder coating waste were investigated. From the most known nine different types of thermoset powder coating systems only products obtained by the hydrolysis of wastes of polyester-epoxy and polyurethane systems were investigated. In addition, effects of mixtures of these two wastes on thermoplastics were also studied. Low and high density polyethylene and polypropylene were selected as the poliolefin systems.