<p>High-entropy alloy coatings have potential applications in surface strengthening and remanufacturing equipment such as metallurgical equipment and energy generation equipment. The high-temperature oxidation resistance of laser-clad NiCoFeCr_xSiAl_yCu_0.5TiMoB_0.4 (x, y = 1.0, 2.0) high-entropy alloy (HEA) coatings was investigated at 800&#xa0;°C. The coatings exhibited a BCC solid solution as the primary phase. Oxidation kinetics revealed that the HEA-Al_2.0Cr_2.0 coating exhibited a significantly lower weight gain (0.26&#xa0;mg/cm²) and a reduced parabolic rate constant (3.75 × 10^-13 g²·cm⁻⁴·s⁻¹) compared to the HEA-Al_1.0Cr_1.0 coating (0.84&#xa0;mg/cm², 3.47 × 10^-13 g²·cm⁻⁴·s⁻¹). An increase in the Al/Cr ratio induced a transition from a multilayered oxide structure to a continuous and dense external Al₂O₃ layer. Thermo-Calc analysis demonstrated that elevated concentrations of Al and Cr result in an approximate 45% increase in their diffusion coefficients within the BCC phase. The increased diffusion flux of Al promotes the development of a continuous and protective oxide layer on the surface. The critical Al concentration required to form a continuous Al₂O₃ layer was 7.97 at.%. The synergistic effect of Al and Cr enhances the oxidation resistance of the high-entropy alloy coating by facilitating Al diffusion and promoting the formation of a stable, protective oxide layer.</p> Graphical abstract <p></p>