A method of producing ethylene oxide comprising: a) providing to a reactor a reactor inlet gas mixture comprising ethylene, oxygen, one or more gas phase promoters, water and carbon dioxide, wherein the one or more gas phase promoters are organic chlorides, the components of the gas mixture subsequently being contacted within the reactor under epoxidation reaction conditions with a catalyst comprising a catalytically effective amount of silver supported on a high purity carrier, a promoting amount of at least one Group IA metal, and a promoting amount of rhenium; b) yielding from the reactor a reactor outlet gas mixture comprising ethylene oxide, ethylene, oxygen, water and carbon dioxide; c) providing at least a portion of the reactor outlet gas mixture to an ethylene oxide absorber to produce an ethylene oxide stream and a treated gas stream comprising water and carbon dioxide; d) providing at least a portion of the treated gas stream to a carbon dioxide absorber unit; e) operating the carbon dioxide absorber unit to produce a recycle gas stream comprising carbon dioxide and water; and f) combining at least a portion of the recycle gas stream from the carbon dioxide absorber unit with fresh feeds comprising oxygen and ethylene and at least a portion of a remaining portion, if any, of the treated gas stream, to form the reactor inlet gas mixture, wherein: (i) a partial pressure of water vapor at the reactor inlet is at least 8 kPa; and (ii) the partial pressure of water vapor at the reactor inlet is continuously maintained at a value of at least 8 kPa over a period corresponding to the production of at least 250 kmole of ethylene oxide per cubic meter of catalyst. a) providing to a reactor a reactor inlet gas mixture comprising ethylene, oxygen, one or more gas phase promoters, water and carbon dioxide, wherein the one or more gas phase promoters are organic chlorides, the components of the gas mixture subsequently being contacted within the reactor under epoxidation reaction conditions with a catalyst comprising a catalytically effective amount of silver supported on a high purity carrier, a promoting amount of at least one Group IA metal, and a promoting amount of rhenium; b) yielding from the reactor a reactor outlet gas mixture comprising ethylene oxide, ethylene, oxygen, water and carbon dioxide; c) providing at least a portion of the reactor outlet gas mixture to an ethylene oxide absorber to produce an ethylene oxide stream and a treated gas stream comprising water and carbon dioxide; d) providing at least a portion of the treated gas stream to a carbon dioxide absorber unit; e) operating the carbon dioxide absorber unit to produce a recycle gas stream comprising carbon dioxide and water; and f) combining at least a portion of the recycle gas stream from the carbon dioxide absorber unit with fresh feeds comprising oxygen and ethylene and at least a portion of a remaining portion, if any, of the treated gas stream, to form the reactor inlet gas mixture, wherein: (i) a partial pressure of water vapor at the reactor inlet is at least 8 kPa; and (ii) the partial pressure of water vapor at the reactor inlet is continuously maintained at a value of at least 8 kPa over a period corresponding to the production of at least 250 kmole of ethylene oxide per cubic meter of catalyst. (i) a partial pressure of water vapor at the reactor inlet is at least 8 kPa; and (ii) the partial pressure of water vapor at the reactor inlet is continuously maintained at a value of at least 8 kPa over a period corresponding to the production of at least 250 kmole of ethylene oxide per cubic meter of catalyst.