Five perovskite-type O carriers were prepd. by compacting the MnO, NiO and SrO or SrCO3 powders at 700-1200 degrees C for 10-20 h. The surface of the grains contained 58.34 to 68.74% of O. The m.p. and O transport capacity of the carriers increased with increasing the Ni content from 1370 degrees C for SrMnO3 up to 1590 degrees C for SrNiO3, and from about 5% up to about 8.5%, resp. After 5 redox cycles, no remarkable decrease in the regenerability of the oxides was obsd. The carriers can be used for chem. looping combustion of fuels.