Electrochemical reduction of CO2 using the electrical energy generated from renewable sources has attracted increasing interest as a potential route for producing high energy Molecules from CO2, In this contribution, high temperature electrochemical reduction of CO2 to CO on a series of transition metal electrocatalysts is studied using DFT,calculations combined with, microkinetic modeling under solid oxide electrolysis cells (SOECs) operating conditions. We show that CO2 dissociation via a two-electron transfer process into adsorbed CO and O2- ions in the electrolyte is favorable on most of the metal electrocatalysts considered, with a dependence of the simulated electrolysis current density on the applied potential consistent with experiinental observations: A "volcano"-type relation between the calculated electrolysis rates and the binding energies of atomic O is found, suggesting that the binding energy of O might be a good activity descriptor for high temperature CO2 electrolysis on transition metals. Our structure-activity trends suggest that metallic Ru and Co would exhibit the highest activity for electrochemical reduction of CO2 in SOECs.