Abstract: Interatomic potentials for tungsten-vanadium (W-V) and tungsten-molybdenum (W-Mo) binary systems have been developed based on Finnis-Sinclair formalism. The potentials are based on an accurate previously developed potential of pure W. Potential parameters of V-V, Mo-Mo, W-V and W-Mo were determined by fitting to a large database of experimental data as well as first principle calculations. These potentials were able to describe various fundamental physical properties of pure V and Mo, such as a lattice constant, cohesive energy, elastic constants, bulk modulus, vacancy and self-interstitial atom formation energies, stacking fault energies and a relative stability of <100> and ½<111> interstitial dislocation loops. Other fundamental properties of the potentials described included alloy behaviours, such as the formation energies of substitutional solute atoms, binding energies between solute atoms and point defects, formation energies and lattice constants of artificial ordered alloys. These results are in reasonable agreement with experimental or first principle results. Based on these results, the developed potentials are suitable for studying point defect properties and can be further used to explore displacement cascade simulations.