In　this　work,　liquid　metal　embrittlement　(LME)　susceptibility　of　12Cr　ferritic/martensitic　(F/M)　thin-walled　tubes　has　been　tested　in　liquid　lead-bismuth　eutectic　(LBE)　under　different　temperatures　(i.e.,　350,　400　and　450　C),　oxygen　concentrations　(i.e.,　oxygen-poor　and　oxygen-saturated)　and　strain　rates　(i.e.,　5　x10(-5),　1　x10(-6)　and　5　x　10(-7)　s(-1)).　The　results　show　that　LME　occurs　under　nearly　all　the　testing　conditions,　and　the　most　influential　factors　upon　the　LME　susceptibility　are　oxygen　concentration　and　strain　rate.　Transmission　electron　microscopy　(TEM)　characterization　at　crack　tips　shows　that　LME　cracks　propagate　preferentially　along　microstructural　boundaries,　such　as　martensite　lath　boundaries,　subgrain　boundaries　and　carbides/lath　interphase　boundaries.