The effect of the type and granulometric composition of the metal components of the core of metal powder wires on their melting characteristics, as well as the quality of formation, properties and structure of coatings obtained by the method of electric-arc welding, is experimentally investigated. Granulated powder of the PG-R6M5 brand with a fraction of 50...300 μm and 200...250 μm is used as the charge components of the core of the experimental wires. As a standard, a powder wire is used, the core of which consists of components in the form of ferroalloy powders, the content of which is calculated to obtain a similar chemical composition to the experimental wires. Electric-arc surfacing is performed on standard equipment under AN-26P flux, observing the same regimes for the correctness of the comparison. Evaluation of the quality of melting of flux-cored wires is determined using the developed methodology based on the determined coefficients of melting, surfacing and losses. The stability of the surfacing process is determined by the dispersion of the instantaneous estimates of the current and voltage values on the arc according to the calculated coefficients of variation. Mode parameters are recorded using a digital recording multimeter equipped with a high-speed analog-to-digital converter. Preparation of samples and investigation of the microstructure of the deposited metal are carried out according to standard methods of metallographic research. As determined experimentally, the use of granulated powder of almost the same, increased size (200...250 μm) as core components of test wires leads to a deterioration in the stability of the electric-arc welding process and, as a result, to an increase in the heterogeneity of the structure of the deposited metal and to an increase in the number of microdefects in it. The greatest stability of the process of surfacing with metal powder wire is achieved, when granulated powder with a fraction of 50...300 μm is used in its core. Due to the same chemical composition and physical properties of the particles of the granulated powder, as well as their lower contamination with harmful impurities compared to the particles of ferroalloys and denser packing in the core of the powder wire compared to a similar powder with a granulation of 200...250 μm, an increase in the uniformity of the structure of the deposited metal and reducing the number of microdefects in it are achieved.