Nanobeam electron diffraction (NBD) is a transmission electron microscopy (TEM) technique that allows determining strain in crystalline materials with a high spatial resolution. In particular, it can be used to measure local strain in the Si channel of metal oxide semiconductor (MOS) devices. In this work, the NBD technique is evaluated with the purpose to optimize its different parameters, such as the thickness of the TEM specimen and the width of the energy filtering window, and to further estimate its precision. Strain is then measured in positive-channel MOS (PMOS) and negative-channel MOS (NMOS) devices with different gate length and Ge or C concentration in the source/drain respectively. The results are compared with optical and electrical characterization, finite-element simulations and to other strain measuring TEM-based techniques. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3546851] All rights reserved.