The intermetallic compound, Re3W is a non-centrosymmetric system with large atomic number (Z) for both constituents (75 for Re and 74 for W) and hence is a good candidate for further study of the correlation of the broken inversion symmetry and the pairing symmetry in this type of system. At Warwick, we have successfully synthesized two distinct superconducting phases (alpha-Mn phase and sigma phase) of Re3W with completely different structures and with different Tc values. We propose to study the superconducting properties of both phases of Re3W using muons as a microscopic probe to determine the penetration depth and study the influence of magnetic fluctuations in these compounds.