Nanoscale palladium and nickel colloids prepared in the presence of certain tetra-n-octylammonium carboxylates contain a high proportion of nonequilibrium trigonal cross section particles. Specifically, those carboxylates which bear a hydroxy function at the a-position, e.g., tetra-n-octylammonium glycolate, exert a strong influence on the shape of the metal colloids. It is shown by an in situ FTIR study of the preparation of colloidal nickel from bis(cyclooctadiene)nickel in the presence of tetra-n-octylammonium glycolate that the interaction of the alpha-hydroxy carboxylate with the surface of the colloidal metal particle is likely to be the morphology-determining factor in the shape-selective preparation of these metal particles.