Kinetic Monte Carlo simulations based on a semi-empirical description of the metal–metal interactions are developed to interpret the formation of a one-dimensional Ni/Pt alloy observed at the step feet of the vicinal Pt(997) surface. Deposition of 0.15 monolayer of Ni atoms at T < 300 K leads to the formation of a (2 × 1) well-ordered nanowire in agreement with scanning tunneling microscopy observations. Exchange process between Ni and Pt atoms at the upper step edge and neighboring influence appear to be the key point to explain such a well-ordered 1D alloy. In addition, a subtle decoration of the step adsorption sites is also necessary.Research highlights► Conditions of bimetallic Ni/Pt alloy formation are demonstrated. ► Drastic experimental conditions should be driven to obtain such regular alloys. ► The stepped surfaces are crucial to guide the alloy formation near steps.