Abstract
Single crystals of K2Pt(CN)4 Br0.3·(H2O)n show a Drude-type optical reflectivity for light polarized parallel to the crystal axis. The energy of the plasma edge indicates a metallic density of free carriers. The relatively small conductivity at dc and low frequencies and the photoconductivity at 4.2oK can be understood in terms of a simple model assuming metallic strands interrupted by lattice defects.