The pyrochlore family seems to be a promising candidate for fuel cells and hydrogen sensors(1) Their structure can be described in a variety of ways. Most commonly, cubic pyrochlores are considered as having a fluorite-type structure with a double unit cell and an ordered deficiency of 1/8 of the oxygen atoms. These empty anion positions raised expectations about the possibility of incorporating high concentrations of hydrogen (by OH?), and of high protonic conductivities. The impedance spectroscopy at various moisture pressures is used to predict the energy activation of the protonic conduction, but no quantification of the atomic fraction of H is available. Moreover, dense samples (> 90%) are be required. The ion beam analysis is to be a powerful tool to quantify light element such as hydrogen. To follow the hydrogen profile, Elastic Recoil Detection Analysis technique has been performed. Such experiment has already been used for perovskite compound (2). We have synthetized nanostructured pyrochlore of Sr doped lanthanum zirconate by the co-precipitation method. Cylindrical pellets were prepared via two different processes: uniaxial pressing (UP) under 250 MPa followed by sintering at different temperature and spark plasma sintering (SPS) process. Thus, several densities were obtained (65-95%). Once the hydrogen profile has been drawn, diffusion coefficient could be estimate by applying the Fick law. The diffusion coefficient is in good agreement with pervious result(3) References : (1) Omata T., Otsuka-Yao-Matsuo S.,. J. Electrochem. Soc. 2001,148, E475?E482. (2) Sorieul S., Miro S., et al., Nucl. Instr. and Meth. B 2008, 266, 1430?1433. (3) Eurenius K. E. J.; Ahlberg E.; Knee C. S. Dalton Transactions 2011, 40, 3946.