A tight binding band structure study of the 1:1 mixed molecular and polymeric conductor (perylene)Co(mnt)(2)(CH2Cl2)(0.5) is reported. It is found that this salt should be a strongly 1D metal with the conductivity originating from the perylene chains. The electron count needed to stabilize the polymeric chain present in this salt is shown to correspond to Co(mnt)(2)(-), and the dimerization gap induced in the HOMO band of the perylene chains is found to be very small. On the basis of these results and by comparison with the known thermopower and transport properties of this salt, it is proposed that the charge transfer from perylene to Co(mnt)(2) should be somewhat smaller than one. A comparison of these results with those for the related 2:1 alpha-(perylene)(2)M(mnt)(2) phases is also reported.