In this article the properties of the electrolyte based on the product of the reaction of methylalumoxane with oligoethyleneglycols are examined. The electrochemical studies were performed to describe the conductivity and lithium transference number of the system. In addition, DSC, SEM, NMR and vibrational spectroscopy studies were used to get a more detailed description of the material. Three classes of electrolytes are here taken into consideration. The first based on the PEGDME liquid oligoether system modified with the MAO–PEGME branched heterocomposite system. The second one is the branched product itself used as an electrolyte matrix. In the last case a crosslinked system was obtained by the utilization of PEGME–PEG mixture. The conductivities obtained were in the range of 10−4 Scm−1 for liquid-like systems and above 10−5 Scm−1 for the solid ones. For samples containing LiCF3SO3 the lithium transference number was higher than 0.5 for some electrolyte compositions while it was in the range of 0.4 for ones containing LiClO4. Electrochemical stability of the system was preliminarily tested by means of cyclic voltammetry.