Two interesting morphology transformations of Au crystals are observed through reacting a mixture of N-alkylimidazole (denoted as C-n-im, where C-n = CrH2n+1, and n = 18 and 1), AgNO3, and HAuCl4 at 200 degrees C The long chain C-18-im with increasing AgNO3 concentration leads to a progressive truncation of octahedrons at (1001 vertices to produce cubes. On the other hand, increasing the concentrations of C-1-im and AgNO3, results in a progressive truncation of octahedrons at {110} edges to give rhombic dodecahedrons, which further transform to the unprecedented tetrahexahedrons. The phenomenon could be understood by considering that while both C-18-im and C-1-im function as a capping agent with preferential adsorption on Au {111} facets, Ag+ adsorbs and is subsequently reduced to Ag on Au (110} facets for the sterically demanding C-18-im, but on the Au (100} facets for C-1-im The competition between the growth of the facets protected by imidazole and Ag controls the morphology transformation via truncation of octahedrons at vertices or edges