A new catalyst composed of Pd nanoparticles supported on MgO has been prepared by the room temperature NaBH(4) reduction of Na(2)PdCl(4) in methanol in the presence of the support. TEM measurements reveal well-dispersed Pd particles of mean diameter 1.7 nm attached to the MgO surface. Further characterization was achieved by ICP-AES, XPS, XRD, H(2) pulse chemisorption and H(2)-TPR. The new catalyst is efficient for the regioselective hydrogenation of the heterocyclic ring of quinolines, as well as for the mild reduction of a variety of alkenes representative of fuel components, and the partial saturation of biodiesel. The new material is considerably more reactive than commercial Pd/SiO(2) and Pd/Al(2)O(3) catalysts under analogous reaction conditions.