Injection　of　CO2　into　subsurface　formations　is　one　of　key　technologies　for　reducing　greenhouse　gas　emissions.　However,　the　injected　CO2　could　cause　migration　of　subsurface　substances,　volatile　organic　contaminants,　for　example,　which　may　threat　ground　water　system　seriously.　Mass　transfer　of　volatile　organic　contaminants　moving　into　CO2　phase　through　interfaces　is　one　of　fundamental　problems　of　safety　assessment　and　risk　analysis　in　CO2　sequestration.　In　this　paper,　we　proposed　a　method　to　calculate　mass　transfer　coefficients　of　the　volatile　contaminant　moving　into　CO2　phase　by　defining　a　length　of　interfacial　mass　transfer　region,　L-IMTR,　on　the　basis　of　the　interphase　mass　transfer　characteristics　of　oil　volatilization　in　CO2-brine-oil　three　phases　in　porous　media.　The　calculation　results　were　compared　with　the　results　obtained　by　numerical　simulations.　The　calculation　results　show　that　the　lumped　mass　transfer　coefficient　K-g　ranges　from　10(-7)　to　10(-2)　l/s,　and　the　mass　transfer　coefficient　k(na)　ranges　from　10(-6)　to　10(-1)　l/s.　By　using　the　proposed　method,　the　interphase　mass　transfer　coefficients　for　the　CO2-brine-oil　three-phase　system　can　be　readily　obtained　without　the　specific　interfacial　areas　between　multiple　phases　known.　(C)　2013　The　Authors.　Published　by　Elsevier　Ltd.　Open　access　under　CC　BY-NC-ND　license.　Selection　and/or　peer-review　under　responsibility　of　GHGT