The development of techniques like spin and dip coating, physical or chemical vapor deposition during the past decades offers now the opportunity for tuning the composition of polycrystalline layers and coating at the nanometric scale. The knowledge of the structure and the microstructure of different layers allow to predict their long term stability under harsh environments. Glancing Incidence X Ray Diffraction technique, based on the variation of the refractive index across the interface between material and air, provides an efficient tool to collect diffraction patterns as a function of the probed depth [1]. As the experimental setup in GIXRD exhibits peculiar features, many corrections need to be applied to extract information about the structure and the microstructure from Rietveld refinement [2]. In this talk, we will firstly discuss those corrections implemented in a Rietveld refinement code and illustrate by different examples[3]. References: [1] see for instance Brunel, De Bergevin, Acta Cryst A42, 299 (1986); [2] D. Simeone, G. Baldinozzi, D. Gosset, G. Zalczer, and J. F. Berar. J. Appl. Crystallography, 44 :1205–1210, 2011 [3] G. Baldinozzi, G. Muller, C. Laberty-Robert, D. Gosset, D. Simeone, and C. Sanchez. J. Phys. Chem.C, 116(14) :7658–7663, 2012.