An alternative process to produce magnetic FePd nanoparticles dispersed in liquid solution exploiting a "top-down" strategy is here reported. This process is based on the solid-state dewetting of a Fe80Pd20 thin film to produce magnetic isolated islands array attached on a solid substrate. The subsequent detachment from the substrate offers the possibility to obtain free-standing magnetic nanoparticles for different applications. An adequate choice of the initial thickness of Fe80Pd20 thin film, annealing time and annealing temperature allows to finely tune the final size and shape of free-standing magnetic nanoparticles. A detailed study on the influence of latter parameters on islands morphology is here presented by SEM images analysis whereas the Johnson-Mehl-Avrami model is employed to extract the kinetics parameters of dewetting process. Room-temperature hysteresis loops and first-order reversal curves are measured in order to investigate the evolution of magnetic properties as a function of dewetting stage