A process for producing ethylene glycol and/or ethylene carbonate, said process comprising contacting at least a portion of a recycle gas stream comprising an alkyl iodide impurity with a guard bed system positioned upstream of an ethylene oxide reactor to produce a treated recycle gas stream, wherein said guard bed system comprises a guard bed material comprising silver on alumina; contacting a feed gas stream comprising ethylene, oxygen and at least a portion of the treated recycle gas stream with an epoxidation catalyst in the ethylene oxide reactor to produce an epoxidation reaction product comprising ethylene oxide; and contacting at least a portion of the epoxidation reaction product comprising ethylene oxide with an aqueous absorbent in the presence of an iodide-containing catalyst in an absorber to produce an aqueous product stream comprising ethylene carbonate and/or ethylene glycol and the recycle gas stream comprising the alkyl iodide impurity, wherein the recycle gas stream supplied to the guard bed system comprises (a) 0.1 to 0.59 mol% of water; and (b) 5 to 90 ppmv of ethylene oxide, based on total recycle gas stream supplied to the guard bed system, wherein the water concentration in the recycle gas stream is controlled by one or more of the type of cooling medium, type of cooling apparatus, temperature of the cooling medium, and the amount of cooling medium used to cool the recycle gas stream leaving the absorber; and wherein the ethylene oxide concentration in the recycle gas stream supplied to the guard bed system is controlled by one or more of regulating the concentration of ethylene oxide in the epoxidation reaction product stream, absorber temperature, absorber pressure, catalyst composition, number of absorber trays, shape of absorber trays, absorbent flow, and absorbent composition in the absorber. contacting at least a portion of a recycle gas stream comprising an alkyl iodide impurity with a guard bed system positioned upstream of an ethylene oxide reactor to produce a treated recycle gas stream, wherein said guard bed system comprises a guard bed material comprising silver on alumina; contacting a feed gas stream comprising ethylene, oxygen and at least a portion of the treated recycle gas stream with an epoxidation catalyst in the ethylene oxide reactor to produce an epoxidation reaction product comprising ethylene oxide; and contacting at least a portion of the epoxidation reaction product comprising ethylene oxide with an aqueous absorbent in the presence of an iodide-containing catalyst in an absorber to produce an aqueous product stream comprising ethylene carbonate and/or ethylene glycol and the recycle gas stream comprising the alkyl iodide impurity, wherein the recycle gas stream supplied to the guard bed system comprises (a) 0.1 to 0.59 mol% of water; and (b) 5 to 90 ppmv of ethylene oxide, (a) 0.1 to 0.59 mol% of water; and (b) 5 to 90 ppmv of ethylene oxide, based on total recycle gas stream supplied to the guard bed system, wherein the water concentration in the recycle gas stream is controlled by one or more of the type of cooling medium, type of cooling apparatus, temperature of the cooling medium, and the amount of cooling medium used to cool the recycle gas stream leaving the absorber; and wherein the ethylene oxide concentration in the recycle gas stream supplied to the guard bed system is controlled by one or more of regulating the concentration of ethylene oxide in the epoxidation reaction product stream, absorber temperature, absorber pressure, catalyst composition, number of absorber trays, shape of absorber trays, absorbent flow, and absorbent composition in the absorber.