Abstract <p>The structure and properties of a nickel–boron coating with an immersion-deposited gold–cobalt film were studied. It has been shown that the application of a thin gold film (30–32 nm) protects the functional nickel–boron coating from oxidation during long-term storage under normal conditions and annealing for 1 h in an air atmosphere in the temperature range of 250–350°C. It has been established that, during annealing of the modified coating, no mutual diffusion of the elements of the substrate and coating occurs. X-ray structural analysis of the modified Ni–B coating showed that the diffraction patterns contain diffraction lines from gold, broadened lines from a solid solution of boron in nickel of the interstitial-substituted type. Low temperature annealing (250–300°C) the Ni–B coating modified with an Au–Co film leads to a decrease in the width of the diffraction lines of the matrix solid solution of boron in nickel, as well as to an increase in the values of its crystal lattice parameter and an increase in the microhardness of the coating to 850–890 HV 0.025. Annealing of the coating at 350°C leads to the release of nanosized particles of the nickel boride phase and is accompanied by a decrease in microhardness to 720–750 HV 0.025. It was concluded that the nickel–boron coating with a gold–cobalt protective film applied after annealing has increased microhardness (850–890 HV 0.025), high wear resistance under boundary friction conditions (linear wear intensity of the coating <i>I</i>_h = 1.6 × 10¹⁰ µm/m) and a low coefficient of friction (<i>f</i> = 0.15), which makes Ni–B/Au–Co coatings comparable in their tribotechnical characteristics to chromium coatings. Modified Ni–B/Au–Co coatings retain the ability to be soldered using low-temperature solder and non-active alcohol–rosin flux, and also have low contact electrical resistance after long-term storage.</p>