The perovskite-type oxides La1-xSrxMO3 (M = Co0.77Bi0.20Pd0.03) have been investigated for three-way catalytic performance and characterized by means of temperature-programmed desorption (TPD), temperature-programmed reduction (TPR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The catalysts exhibited good activity in CO elimination: La0.8Sr0.2MO3 showed ca. 100% CO conversion at 160 degreesC, 60 000 h(-1), and lambda = 1.00. Under similar reaction conditions, the activity for C3H6 elimination decreased in the order of La0.2Sr0.8MO3 > La0.8Sr0.2MO3 > La0.4Sr0.6MO3 > La0.6Sr0.4MO3 > LaMO3, while the activity for NO elimination decreased in the order of La0.8Sr0.2MO3 > La0.2Sr0.8MO3 > La0.4Sr0.6MO3 > La0.06Sr0.4MO3 > LaMO3. With x < 0.6, La1-xSrxMO3 were single-phase and hexagonal in structure; at x = 0.6 and 0.8, they were cubic and there was a trace amount of the La2O3 phase. The results of TPD, TPR, and XPS studies revealed the coexistence of over-stoichiometric oxygen vacancies in La0.8Sr0.2MO3, a criterion for good three-way catalytic performance.