Li1.3AlyYx - yTi1.7(PO4)(3) (x = 03; y = 0.1. 0.2) solid electrolyte compounds were synthesized by solid state reaction and studied by X-ray diffraction. At room temperature the compounds belong to a rhombohedral symmetry (space group R (3) over barc) with six formula units in the unit cell. Ti 2p, O 1s, P 2p, Li 1s. Y 3d, and Al 2p core level XP spectra at Li1.3AlyYx - yTi1.7(PO4)(3) (X = 0.3; y = 0.1. 0.2) ceramic surfaces have been determined by XPS. The measurements of the electrical properties of the ceramic samples in the frequency range 10 Hz-1 MHz were carried out by a two probe method and a four probe method. The measurements in the microwave range (3. 10(5)-3. 10(9)) Hz were performed in a coaxial line, the part of the inner conductor which was replaced by the sample. The investigation of the electrical properties of the ceramic samples was carried out in air in the temperature range (300 to 700) K. The increase of the stoichiometric factor y of the compounds leads to the increase in the total and bulk conductivities of ceramics and decreases their activation energies. (C) 2012 Elsevier B.V. All rights reserved.