We report a nanolithography technique that allows simultaneous direct control of the local chemistry and topography of thin polymer films. Specifically, a heated atomic force microscope (AFM) tip can write sub-15 nm hydrophilic features onto a hydrophobic polymer at the rate of 1.4 mm per s. The thermally activated chemical reactions and topography changes depend on the chemical composition of the polymer, the raster speed, the temperature at the AFM tip/sample interface, and the normal load. This method is conceptually simple, direct, extremely rapid, achievable in a range of environments, and potentially adaptable to other materials systems.