Abstract: Alloys based on the Cu-Ag-Co system are of significant technological and scientific interest due to the limited mutual solubility of all three elements, which leads to complex microstructural behavior. In this work, we present the new classical interatomic potential for this system that accurately reproduces basic thermodynamic and kinetic properties, achieving an accuracy comparable to that of modern machine learning interatomic models. The potential is formulated in a classical functional form, which provides high computational efficiency and makes it well-suited for large-scale molecular dynamics simulations. As an example of application, we investigate atomic diffusion and precipitation in Cu-Ag-Co alloys. The model reproduces key trends in both self- and impurity diffusion, including the inverse correlation between diffusivity and melting temperature and the strong suppression of Co diffusion in the considered metals.