Fumed　silica　(F-SiO2)　particles　were　hydrophobized　in　situ　in　aqueous　solutions　of　alkanediyl-α,　ω-　bis(dodecyldimethylammoniumbromide)　(12-s-12,　s　=　2,　6)　gemini　surfactants.　This　process　was　assessed　using　zeta　potential　measurements.　The　particles　were　found　to　transit　from　their　original　hydrophilic　nature　to　hydrophobic　and　then　back　to　hydrophilic　with　increases　in　the　surfactant　concentration　(C).　The　hydrophobic　particles　could　spontaneously　adsorb　at　the　air/water　interface,　resulting　in　significant　stabilization　of　aqueous　foams.　The　re-hydrophilic　particles　desorbed　from　the　interface,　leaving　only　surfactant　molecules　to　stabilize　the　foam.　The　strong　interfacial　elasticity　of　the　surface　films　was　reflected　in　the　highly　stable　foams.　The　length　of　the　surfactant　spacer　also　affected　the　adsorption　of　the　gemini　surfactant　on　the　F-SiO2　particles,　and　therefore　had　an　effect　on　the　elasticity　of　the　adsorbed　film　and　the　stability　of　the　foam.　The　12-2-12　surfactant,　having　a　relatively　short　spacer,　carried　less　positive　charges　because　of　the　incomplete　dissociation　of　its　counter　ions,　resulting　in　less　initial　adsorption　on　the　F-SiO2　particles　compared　with　the　12-6-12,　but　eventually　formed　a　denser　monomeric　layer　because　of　decreased　repulsion　between　the　adsorbed　molecules.　The　12-2-12　exhibited　stronger　adsorption　at　the　air/water　interface;　therefore,　the　synergistic　action　of　the　F-SiO2　particles　together　with　the　12-2-12　produced　better　foam　stabilization　compared　with　the　12-6-12.　©　Editorial　office　of　Acta　Physico-Chimica　Sinica.