The powders of Li1.3Sc0.15Y0.15Ti1.7(PO4)(3) Were synthesized by a solid phase reaction. The sintering duration of the ceramic samples was varied from 0.25 h to 3 It and studied by X-ray and impedance spectroscopy in the frequency range from 10 Hz to 1.2 x 109 Hz at temperatures up to 600 K. Two relaxation dispersions of the electrical parameters were found and analysed in terms of bulk and grain boundary ionic transport processes. Varying of the sintering duration affects the density of the ceramics, sizes of grains, values of the total conductivity (sigma(t)) and its activation energy (Delta E-t). The bulk conductivity (sigma(b)) and its activation energy (Delta E-b) in average do not depend on duration of sintering. (c) 2005 Elsevier B.V. All rights reserved.