The quality of a thermal spray coating or any other material is determined to a large extent by its chemical and phase constitution and structure. Many researchers have addressed the microstructure of HVOF coatings and relationships of their properties to feedstock powder structure. A comparative study of the microstructure, phase properties, hardness, and wear resistance of HP/HVOF sprayed layers is presented. The layers were produced by the JP-5000 method using powders with the composition WC-12% Co and WC-17% Co. The influence of the amorphous phase, the carbide grain size, and the degree of oxidation on the wear resistance of the layers is discussed. Spray parameters are statistically evaluated using the design-of-experiments method. Several different powders with varying particle size distribution and particle morphology are investigated. Paper includes a German-language abstract.