The synthesis of nanocrystals is the core of the nanoscience. The highly controlled nanomaterials are desirable for the studies of catalysis, in order to unambiguously correlate the catalytic properties with the structure and composition of catalysts. In this thesis, highly controlled nanocrystals are synthesized through solution phase synthesis. Shape controlled nanocrystals can be synthesized as cubes, octahedra, icosahedra, truncated cubes, cuboctahedra tetrapods, octapods and spheres. The nanocrystals with these morphologies selectively expose {100} and/or {111} facets as well as high-index facets, thus enabling various investigations of structure sensitive catalysis at the nanoscale. In addition to the shape control, the composition of metal catalysts is also tunable by making alloy or intermetallic nanocrystals. The nanocrystals of Pt-Mn, Pt-Fe, Pt-Co, Pt-Ni, Pt-Cu, Pt-Zn, Pt-Pb, Pt3Mn, Pt3Fe, Pt3Co, Pt3Ni, Pt3Zn, Pt3Pb, FePt, and etc. allow the fundamental exploration of catalysis. Oxides, heterostructures, as well as artificial crystals which have a long range ordered crystalline structure, are also prepared. These highly controlled nanomaterials have been demonstrated as ideal model materials for studies of catalysis. In this thesis, formic acid and methanol electrooxidation, oxygen reduction reaction, oxygen storage, CO oxidation, and enhanced stability are discussed.