In this work, thick films of Perovskite LaLiTiO (LLTO) and Li-NASICON LiAlTi(PO) (LATP) Li-conductors have been prepared by tape casting and their microstructure and homogeneity assessed by SEM and confocal Raman spectroscopy. Electrical properties of thick films have been investigated by Impedance spectroscopy. In particular, bulk, grain-boundary and electrode contributions to conductivity have been differentiated as a function of frequency. However, modifications on the grainboundary chemistry affects considerably ion conductivity of films. The confocal Raman spectroscopy results allowed the observation of the resulting phases particles connectivity in thick films and a better understanding of ionic conductivity results in relation with the samples heterogeneity. In LLTO films, the reactivity of the film particles against water leads to formation of hydroxyl groups that decreases the Li mobility at the particles surface after sintering. In LTAP films the formation of a high conducting grain-boundary phase leads to improve total conductivity values making thick films promising candidates for application in all solid state Li secondary batteries.