CaRuO3, perovskite-based lead-free thick-film resstors were processed on 96%-alumina and Low Temperature Co-fired Ceramic (LTCC) substrates. The microstructure evolution, possible interaction and electrical properties of resistors were ivestigated. TFR with 25% by vol. of ruthenate on alumina exhibit a sheet resistance Rs=5 KOhm/sqwith hot and cold TCR of 225 and 470 ppm/degree C respectively, whereas the same composition gives 1.2 KOhm/sq and 16.5 KOhm/sq. for cofired and postfired samples, respectively, on LTCC, wuth hot and cold TCR of 190 and 314 ppm/degreeC for co-fired structures, and 216 and 250-ppm/degreeC for post-fired LTCC structires.