Crystals of [Pt2(n-pentylCS2)4I] show a transition from semiconductor to metallic with the increase of the temperature (conductivity is 0.3–1.4 S · cm−1 at room temperature) and a second metallic–metallic transition at 330 K, inferred by electrical conductivity measurements. X-ray diffraction studies carried out at different temperatures (100, 298, and 350 K) confirm the presence of three different phases. The valence-ordering of these phases is analyzed using structural, magnetic, and electrical data. Density functional theory calculations allow a further analysis of the band structure derived for each phase. Nanostructures adsorbed on an insulating surface show electrical conductivity. These results suggest that MMX-polymer-based nanowires could be suitable for device applications.