Wet- environmental transmission electron microscopy studies of heterogeneous hydrogenation of complex nitriles in a liquid phase over new mesoporous cobalt- promoted ruthenium nanocatalysts on reducible nanotitania supports are presented. The desorbed organic products in the dynamic liquid phase hydrogenation are imaged situ on the nanoscale. The direct studies on the "nanocomposite" catalysts are correlated with parallel reaction chemistry measurements. They demonstrate high hydrogenation activity at low operating temperatures in the presence of atomic scale anion vacancy defects associated with Lewis acid sites at the nanosupport surface and an electronic and synergistic contribution to the promoter mechanism. The combined synergistic effect between the two metals and the interaction with the reduced nanosupport leading to an electronic modi. cation lead to highly reactive site for the hydrogenation catalysis. The results illustrate novel selective hydrogenation chemistry with mesoporous nanocatalyst systems on nanosupports.