The　micellization　of　Cl　1pPHCNa,　a　carboxylated　gemini　surfactant　with　an　p-Oxybenzene　residue　in　the　spacer,　in　aqueous　solution　at　pH　12　was　characterized　by　the　absorption　and　the　fluorescence　spectra　of　the　p-Oxybenzene　residue.　The　critical　micelle　concentration　of　Cl　1pPHCNa　was　determined　by　the　absorption　spectra　to　be　0.0940　mmol　L-1,　which　agreed　well　with　that　measured　by　surface　tension　technique.　The　fluorescent　intensity　of　Cl　1pPHCNa　aqueous　solution　rapidly　increased　with　increasing　Cl　1pPHCNa　concentration　(C)　then　reduced　when　C　was　beyond　0.45　mmol　L-1,　which　meant　the　self-quenching　occurring.　At　fixed　C,　the　time-resolved　and　the　steady-state　fluorescence　quenching　with　the　p-Oxybenzene　residue　as　the　intrinsic　probe　and　with　methyl　viologen　(MV2+)　as　the　extrinsic　quencher　could　be　used　to　measure　the　aggregation　number　(N)　of　Cl　1pPHCNa　micelle.　The　results　showed　the　N　for　the　micelle　formed　at　C　=　1.5　mmol　L-1　was　14.5　and　gradually　increased　with　further　increasing　C.　This　indicated　the　more　and　more　molecules　packed　within　a　micelle　with　increasing　C,　which　explained　well　the　fluorescence　self-quenching　when　C　was　beyond　0.45　mmol　L-1.　(c)　2007　Elsevier　B.V.　All　rights　reserved.