Important progress and breakthrough developments in materials science, biology and medicine are more and more often hampered by the absence of adequate analysis techniques. In particular, an analytical tool allowing a mapping of samples with both excellent resolution and high-sensitivity chemical information is cruelly missing. On the one hand, Transmission Electron Microscopy (TEM) is providing high-resolution images (sub-Ångström level), but chemical information is limited in sensitivity in the % range. On the other hand, Secondary Ion Mass Spectrometry (SIMS) is an extremely sensitive technique (ppm-ppb range), but its lateral resolution is limited to 50nm. It is important to note that physical limitations (dimensions of collision cascades, number of atoms in a pixel) will never allow SIMS resolutions better than 10nm.Parallel Ion and Electron Spectrometry (PIES) would allow to go beyond these limitations. The PIES project therefore aims at developing a new instrument allowing simultaneous and in-situ ion and electron spectrometry in order to correlate structural information at a level of 1nm with highly sensitive chemical information. This new instrument will therefore be able to combine the unique advantages of SIMS and TEM. The PIES technique will give the possibility to dig in the small size applications, out of our range at the present time.The unique performances of PIES would make it a booster for future developments in materials science, biology and medicine:•Perfect superposition of TEM and SIMS images recorded simultaneously and in-situ allowing for high resolution (1nm scale) – high sensitivity (ppm range) elemental mapping.•3D analytical characterization of layered and complex samples by combining 2D TEM data with depth-resolved SIMS data. A complete 3D structural and elemental characterization with high resolution and high sensitivity can thus be performed.•PIES data will be quantitative: while the major elements are quantified by the PIES instrument’s EELS (Electron Energy Loss Spectroscopy) system in the scanning TEM (STEM) or energy filtering (EFTEM) mode, the minor elements detected via the secondary ion signal will be quantified using the “minor/major ratio” of secondary ion signals and the EELS data for calibration. As a consequence, both the matrix effect of traditional SIMS and the poor detection limits of EELS can be overcome by PIES.•The PIES instrument allows the recording of isotopic ratio images with excellent lateral resolution.•Precise calibration of the local erosion rates resulting from the primary ion bombardment thanks to the in-situ determination of sample thickness by energy filtering TEM. As a consequence, the depth scale while performing 3D mapping can be quantitatively monitored.•Use of the primary ion gun to optimize the TEM sample preparation in-situ.This project consists in an analytical and instrumental approach towards parallel ion and electron spectrometry. On the analytical side, complementary SIMS and TEM/STEM analyses using standalone SIMS and TEM/STEM instruments will be performed on well-chosen samples in order to study and highlight the spatial resolution and quantification aspects. The instrumental workpackages, which are realized in parallel, focus on the optical calculation, the design, the manufacturing and the testing of the heart of the PIES instrument (near-sample region with TEM components, primary ion bombardment and secondary ion extraction).