Large-area free-standing Pt rods have been prepared successfully by simply annealing in air platinum films deposited on a sapphire substrate. This paper describes the first examples of the growth of these Pt rods. The Pt rod density is about 2 × 10⁶ cm⁻² and the longest Pt rod grown at an angle on sapphire was over a hundred micrometres long. From the ample results of SEM images coupled with the kinetics data, coarsened Pt particles obey the classical ripening process for the first short annealing time, but then followed a vapour–solid growth mode, leading to the formation of Pt rods during the later stages of annealing. Electrical measurements indicate that Pt rods had a resistivity of 10 μΩ cm as well as that of bulk platinum. The electron field emission of Pt rods can be turned on at 5 V μm⁻¹, achieving a maximum current density of 4 mA cm⁻² at an applied field of 33 V μm⁻¹. As far as we know, this is the first investigation of the electron field emission properties of Pt rods. Through use of simple thermal annealing processes to prepare free-standing Pt rods, it is promising for future nanoscale device fabrication.