Complex proton conductors based upon metal-organic frameworks (MOFs) have attracted increasing interests for applications in fuel cells. We have developed new proton conductors based on stable and functionalised MOFs [MFM-300 (Cr) and MFM-300 (Cr)-SO3H]. Importantly, MFM-300(Cr)-SO3H exhibited remarkable proton conductivity (>10-2 S/cm at 25 oC under 98%RH), which is comparable with the current leading commercial material based upon Nifion polymers (10-1 S/cm at 60 to 80 oC under 98%RH). We request 7 days on IRIS...