The development of β-metastable titanium alloys that combine low Young's modulus, good mechanical properties, corrosion resistance and biocompatibility has attracted industry interest. This type of alloy is an alternative to commercial alloys such as Ti-6Al-4V, avoiding the cytotoxic effect that occurs with Al and V in the human body in the manufactured orthopedic prostheses. In this scenario, the present work aims to characterize the effect of Nb concentration in the properties of Ti alloys based on the Ti-12Mo-xNb stoichiometry (x = 0, 3, 8, 13, 17 and 20). All alloys were produced by arc melting with non-consumable tungsten electrode in an argon atmosphere and the ingots were characterized by x-ray diffraction (XRD), optical microscopy (OM), Vickers microhardness and Young's modulus was measured by impulse excitation and density was measured using the Archimedes' principle. The Ti-12Mo alloy and the Ti-12Mo-20Nb alloy showed the lowest Young's modulus. The best hardness/ modulus was found for the Ti-12Mo-3Nb alloy. All the alloys studied in this work showed hardness/ modulus ratio above the traditional Ti-6Al-4V alloy (2.85), presented great potential for the biomedical application.