It　has　been　known　for　decades　that　nanopores　produced　by　selective　leaching　during　galvanic　corrosion　can　lead　to　dramatic　loss　of　materials　ductility　and　strength　under　tension.　However,　the　underlying　atomic　mechanisms　of　the　nanopore　induced　embrittlement　remain　to　be　poorly　known.　Here　we　report　in　situ　observations　of　the　deformation　and　failure　of　dealloyed　nanoporous　gold　by　utilizing　the　state-of-the　art　aberration-corrected　transmission　electron　microscopy　and　fast　direct　electron　detection　camera.　Our　time-resolved　atomic　observations　reveal　that　the　brittle　failure　of　the　nanoporous　gold　originates　from　plastic　instability　of　individual　gold　ligaments　by　the　interplay　between　dislocation　plasticity　and　stress-driving　surface　diffusion.　(C)　2018　Acta　Materialia　Inc.　Published　by　Elsevier　Ltd.　All　rights　reserved.