A method of synthesizing semiconductor nanostructures of at least one semiconductor material (e.g. nanowires, nanorods, nanoribbons, nanodots, quantumdots, etc.) is described which includes the steps of placing a solid catalyst particle on a substrate, placing the combination of the said substrate and the said solid catalyst in a chamber of low oxygen partial pressure, below I×10−2 mbar, adding one or more gaseous reactants comprising at least one of said semiconductor material and a suitable precursor therefor and heating the said combination to a temperature above 200° C. but below the melting point of the solid catalyst particle. Nanostructures made by the method are also claimed.