There is provided a process for the enhanced recovery of oil from oil bearing strata with gaseous or liquid form of carbon dioxide, the improvement which comprises prior to or simultaneously with the injection of carbon dioxide, injecting into the strata in a single slug or in a plurality of slugs a material consisting essentially of at least one compound which has a clay-effect inhibiting cation with a hydrated ion diameter of from about 0.136 to about 0.15 nm and a coordination number of 12, in a concentration number of 12, in a concentration of from about 0.001 mol to about 50 mol.