In this study, the optical and electrical properties of undoped and Sr-doped SmCoO3 (Sm0.5Sr0.5CoO3) thin films were investigated. Dense, transparent films with the thickness of 80-110 nm were prepared on sapphire substrates using a polymeric precursor spin coating technique. Films were annealed from 500 to 800 degreesC to alter their microstructure, and the onset of crystallization (perovskite structure) was observed for the 600 degreesC annealing temperature. The electrical conductivity of SmCoO3 and Sm0.5Sr0.5CoO3 thin films was measured as a function of temperature. The effect of Sr dopant turned out to increase conductivity by two orders of magnitude and decrease the activation energy. The results of optical measurements showed that the shape of the optical spectra changed as the structure changed from amorphous to crystalline. The comparison of electrical and optical measurements suggested that this absorption could be related to the charge carrier concentration. (C) 2004 Elsevier B.V. All rights reserved.