X-ray absorption spectroscopy at the Co K edge was used to study the Co coordination in CoBr2 (PEO)(16) and [0.45 CoBr2 + 0.55 LiBr](PEO)(16) at 25 degrees C. In CoBr2 (PEO)(16) the salt consists of mostly undissociated CoBr2 coordinated with six oxygens from the PEG. The respective Co-Br and Co-O bond lengths are 2.36 Angstrom, and 2.49 Angstrom. In [0.45 CoBr2 + 0.55 LiBr](PEO)(16) the Co is coordinated with three Br atoms with a bond distance of 2.40 Angstrom and between two and three O atoms with a bond distance of 2.27 Angstrom. On the addition of LiBr the Co coordination changes from a mixture of octahedral and tetrahedral species to exclusively tetrahedral coordination. The anomalous conductivity behaviour of the mixed salt CoBr2/LiBr-(PEO) complex is related to the formation of CoBr3- complexes and a reduction in crosslinking of the PEO by the CoBr2.