Abstract: A process prepares an oxygen carrier for a chemical looping process including providing a material A having a first transition metal and/or an oxide of the first transition metal. The first transition metal is selected from chemical element groups 6-11 of the Periodic System. Material A is subjected to a reaction with H2 to reduce the first transition metal and/or oxide to form a reduced material B. Material B is treated with a salt solution of a second transition metal selected to have a standard reduction potential larger than the first transition metal. A portion of the first transition metal in the reduced material B is replaced by the second transition metal. A molar ratio of the first transition metal with respect to the second transition metal in material B ranges between 2:1 and 100:1. An oxygen carrier is obtained with the method and is regenerated using steam.