Diffraction gratings with micron and submicron periods have many applications such as modifying optical waveguide characteristics, forming alignment layers for liquid crystals, and as building blocks for pattern precursor substrates used in various applications. In this paper, we describe a single step dry-etching process for the fabrication of diffraction gratings on selected commercial polymers using two coherent interfering 248 nm KrF laser beams. Grating periods from 0.2 ?m to several ?m were created with single and multiple laser pulses by varying the angle between the two interfering laser beams. Grating structures were characterized using laser diffraction, Scanning Electron Microscopy, and Atomic Force Microscopy. Three plastics were investigated (BCB, PAI, and PET) and it was found that the highest quality gratings formed on PET films.