This　paper　reports　the　investigation　about　the　effect　of　the　alkyl　tail　length　of　quaternary　gemini　surfactants,　2-hydroxyl-propanediyl-alpha,omega-bis(dimethylalkylammonium　bromide),　referred　to　as　m-3(OH)-m,　where　m　represents　the　number　of　carbon　atoms　at　each　alkyl　tail,　on　the　foamability　and　foam　stability.　To　understand　the　foaming　behavior,　the　adsorption　of　surfactants　at　the　air/water　interface　as　well　as　the　dilational　viscoelasticity　of　their　films　was　studied　using　surface　tension　and　dilational　interfacial　rheology　measurements.　14-3(OH)-14　was　found　to　have　stronger　foamability　and　stabilize　more　efficiently　the　foam　than　12-3(OH)-12,　however,　16-3(OH)-16　failed　to　generate　foam.　The　latter　was　attributed　to　the　self-coiling　of　the　long　hexadecyl　tails　prior　to　the　adsorption　of　surfactant　at　the　air/water　interface,　resulting　in　the　ageing　effect　of　the　adsorption　behavior.　For　both　12-3(OH)-12　and　14-3(OH)-14,　the　results　revealed　a　good　correlation　between　the　high　limit　interfacial　elasticity　and　high　stability　of　foam　at　the　level　of　identical　surface　excesses.　(C)　2011　Elsevier　B.V.　All　rights　reserved.