The invention relates to dispersions of artificial oxygen carriers, wherein the dispersions contain capsules with reversible oxygen storage capacity, the capsules comprising an oxygen-permeable capsule material, that contains and/or encloses fluorinated, particularly perfluorinated hydrocarbons, preferably perfluorocarbons. The dispersions are particularly suitable as a blood substitute, preferably for the purpose of transfusion, e.g. in states of blood loss of the human or animal body, in particular following surgical interventions, accidents, injuries etc, or for the prophylactic treatment and/or treatment by therapy of ischaemic states or states following a reperfusion.