\The residual strain in a-Si:H layers has been determined directly using synchrotron radiation diffraction, at LNLS in Brazil, by two different methodologies. Using a method previously presented using laboratory X-ray sources, the height and length of side of the Si-Si-4 tetrahedron are determined from variations in the diffraction angle of the first two amorphous peaks. In a more extensive calculation, the spatially dependent pair correlation function is calculated, allowing the separation of strain resulting from changes in the bond length and the bond angle. Two different layers, deposited by HW-CVD oil glass substrates at growth temperatures of 300 and 500 degrees C, have been studied to investigate the effect of growth temperature on residual stress. (c) 2005 Elsevier B.V. All rights reserved.