Harnessing　the　selectivity　in　catalytic　hydrogenation　of　CO2　is　important　for　producing　valuable　chemicals.　Herein,　the　shape　dependency　of　the　CO2　hydrogenation　on　singly　dispersed　Ru/CeO2　catalysts　is　investigated.　CeO2　of　three　shapes,　including　nanocube,　nanooctahedron　and　nanorod,　are　prepared　as　the　catalyst　supports　and　assigned　to　the　surface　of　(100),　(111)　and　(110)　crystal　plane,　respectively.　The　Ru/CeO2　(nanorod)　exhibits　the　highest　selectivity　to　CO　(97.6　%)　at　350　degrees　C,　while　the　Ru/CeO2　(nanocube)　exhibits　a　mediocre　selectivity　to　CO　(41.4　%)　but　the　highest　CO2　conversion.　The　shape　of　the　CeO2　support　determines　the　electronic　state　of　supported　Ru　atoms　through　the　electronic　metal-support　interaction.　The　low　CO　affinity　on　cationic　Ru-beta　sites　leads　to　the　higher　selectivity　to　CO　on　the　Ru/CeO2　(nanorod)　and　Ru/CeO2　(nanooctahedron)　catalysts,　while　the　strong　dissociation　ability　of　H-2　on　low　valence　Ru-alpha　sites　results　in　the　high　activity　on　the　Ru/CeO2　(nanocube)　catalyst.