Recent advances in the design and preparation of platinum-based nanostructures and their applications as electrocatalysts for tow-temperature fuel. cells are reviewed. Discussions are focused on the fundamental understanding and new experimental designs in the control of shape, composition and nanoscale structure of platinum and its alloy particles in colloidal systems. We explain the formation of various heteronanostructures using the Frank-van der Merwe (FM), Volmer-Weber (VW) and Stranski-Krastanov (SK) growth modes. Phenomena that exist in nanometer-sized regime, such as the disappearance of miscibility gaps for certain platinum alloys are given special attentions. The relationship between electronic structure or surface atomic arrangement and catalytic properties of platinum-based nanostructures is discussed. (C) 2008 Elsevier Ltd. All rights reserved.