We have studied the interfacial properties of phase separating binary system using Monte Carlo simulations. In the model, we have considered vacancy-assisted phase separation and implemented residence time Monte Carlo algorithm. We have taken an A-B binary alloy with a highly diluted vacancy concentration on a rigid lattice with face-centered-cubic structure. We have calculated the equilibrium thermodynamic properties of (100), (110) and (111) interfaces, and computed the interfacial free energy using a direct thermodynamic integration. We have also studied the effect of temperature and interaction parameters on interfacial free energy, width and roughness. We determined the equilibrium shapes of precipitates from the simulations and compared them with the corresponding Wulff shapes. The equilibrium precipitate shapes differ from the Wulff shapes and this deviation is attributed to the roughness of the interface.