An　experimental　study　on　volatile　organic　compounds　(VOCs)　removal　with　non-thermal　plasma　generated　by　dielectric　barrier　discharge　(DBD)　in　a　coaxial　cylindrical　reactor　was　carried　out　at　atmospheric　pressure　and　room　temperature.　During　plasma　processing　to　decompose　toluene,　electrical　parameters　such　as　discharge　power,　equivalent　capacitance　of　the　gap　(Cg)　and　the　dielectric　barrier　(Cd),　were　analyzed　using　the　Q　-V　Lissajous　diagram.　In　order　to　optimize　the　geometry　of　the　DBD　reactor,　the　removal　efficiency　of　toluene　was　compared　for　various　inner　electrode　diameters　(1.20mm,　1.65mm,　2.0mm)　and　different　reactor　materials　(ceramic　and　PMMA).　It　suggested　that,　the　specific　input　energy　(SIE)　depended　linearly　on　the　voltage　in　all　cases,　and　Cg　decreased　with　increasing　voltage　and　gap　length.　However,　with　the　voltage　increasing,　Cd　increased　initially　and　stabilized　at　about　700　pF.　With　respect　to　toluene　conversion,　2.0mm　electrode　appeared　to　be　superior　to　1.20mm　and　1.65mm　electrodes.　In　contrast　to　PMMA　reactor,　abatement　of　toluene　was　enhanced　by　ceramic　reactor　possessing　high　permittivity,　especially　in　the　high　input　energy　condition,　73%　for　ceramic　and　62%　for　PMMA　at　660J/l.　The　energy　efficiency　for　toluene　removal　stabilized　at　5　g/kWh　approximately　with　removal　ratio　exceeding　50%.　©　Crown　Copyright.