Magnesium phosphide (Mg3P2) microstructures having microwire shapes with ultrahigh-aspect-ratio and three-dimensional (3D) urchin, flower, and branched shapes (myriapod or leaf) are synthesized using a one-step reaction without any catalysts or templates. The microstructures with different shapes are easily controlled through various temperatures. With increasing reaction temperature, the morphology of Mg3P2 microstructures changes from microwires with ultrahigh-aspect-ratio to branched shapes similar to myriapods or leaves. The growth mechanisms of these microstructures are discussed in detail. (C) 2012 Elsevier B.V. All rights reserved.