Palladium nano-spheres 160 nm in diameter, as an assembly of uniform 5 nm nanoparticles, are accessible using a facile one step method under continuous flow on a spinning disc with hydrogen gas as the reducing agent. The stable colloidal system is an effective catalyst for the Mizoroki–Heck reaction, as established for the reaction between several aryl halides and n-butyl acrylate, and can be readily recycled without a change in their catalytic activity.