Nanostructured materials possess interesting physical and chemical properties which may differ significantly from their macroscopic counterparts. Understanding the size and shape dependence of nanostructures is important to the rational design of nanomaterials with a desired functionality. Scanning probe microscopy and its derivatives provide unique opportunities to deepen our insight into the electrical characteristics of nanostructures. We have developed several new approaches based on electric force microscopy that enable quantitative characterization of the electrical properties of nanostructured materials. Some example applications include the measurement of the characteristic capacitance of the EFM tip,the surface charge density of materials,and the charge carrier density in graphene and ultrathin organic films.