Lithium transition metal oxides LiMO2 (M=Co and Ni) are used as cathode materials for high voltage lithium batteries. In order to improve the electrochemical properties we have successfully synthetized Li3Co2-xNixRuO6 (x=0, 1, 2) compounds, which adopt the LiCoO2-type, S.G. R-3m, for x=0 and 1 values. When x=2 the so-called Li2TiO3-type is obtained. The incorporation of Ru to these structures provokes the onset of new interesting magnetic properties. Our preliminary bulk magnetic studies reveal the onset of ferromagnetic behaviour in the case of Li3Ni2RuO6 with a Tc=100 K; while in the case of Li3Co2RuO6 and Li3CoNiRuO6 an antiferromagnetic behaviour has been observed with a TN around 10 K. The D2B diffractometer will be the ideal tool to determine the structure of these compounds, where the knowledge of the Li content will be crucial to understand the electrochemical and magnetic properties of these compounds. The determination of the magnetic structure of these oxides is also one of the aims of this proposal and the D1B diffractometer equipped with a orange cryostat is also requested.