Two self-assembled isostructural functionalized metal-organic nanotubes have been synthesized using 5-triazole isophthalic acid (5-TIA) with In(iii) and Cd(ii). In- and Cd-5TIA possess one-dimensional (1D) nanotubular architecture and show proton conductivity along regular 1D channels, measured as 5.35 × 10-5 and 3.61 × 10-3 S cm-1 respectively. © 2012 The Royal Society of Chemistry.