Two decades after the first publications, MALDI ions sources for Mass Spectrometry (MS) are clearly an incontrovertible tool for analytical purposed. MALDI as ESI ion sources, by allowing obtaining ions from high masses polar compounds in the gas phases, have become of specific interest in analysis of biomolecules. There important role in proteomics studies has nowadays no more to be demonstrated and is revealed by the number of publications in the field where such technologies are used. MALDI is a robust, sensitive, easy technology with complementary performances to ESI. It has the advantage to work with solid samples submitted to laser irradiation that allow for the introduction and analysis of samples under various forms from solutions to small pieces of materials. One benefit of MALDI has appeared a decade ago with its use for retrieving molecular information from tissue sections allowing for obtaining molecular information's at a specific location on the surface reflecting its local composition. Adding automation of tissue section analysis and by developing dedicated bioinformatics' tools, access to molecular images of the distribution of analyzed specie in the tissue was obtained. After several years of developments, MALDI Imaging Mass Spectrometry (MALDI-IMS) is now a tool for researches in the field of proteomics with many applications ranging from fundamental biological problems to clinical applications. MALDI-IMS does present several advantages namely achievement in one acquisition of as many images as detected compounds without any prerequisite knowledge, suppression of time and material consuming steps of extraction and separation, added information of molecules localization after their identification. Recent published applications of MALDI-IMS give a good overview of the interest of such a technology for biological applications. Although, if MALDI-MS in peculiar or MALDI in general is a performing tool, fundamental processes that lead to formation of ions in the gas phases are still not clearly understood. In fact, in MALDI, as in others desorption techniques (FAB, PDMS, SIMS) only few control of the processes leading to ion formation is possible. In MALDI, desorption/ionization process lead to the formation of a plasma that user cannot affect consequently expect or weakly by changing laser fluence or matrix used. More, than just aiming in satisfying a scientific curiosity, better understanding of fundamental processes is the key to obtain fully controlled desorption/ionization for higher analytical performances namely sensitivity, signal to noise ratio, resolution and range of observed species. In fact, fundamental studies of MALDI at its beginning prove that only few percent of the material ablated after a laser shot is present as ions. Thus, increasing number of ion produced is one of the aspects where much of the effort must be drawn. On the other side, it was proved several years ago that ions present in the gas phase just after the desorption event present themselves as clusters of molecules i.e. analytes molecules surrounded by matrix molecules. These clusters do not seem to desolvate easily inducing chemical noise background in the mass spectra. Controlling these clusters desolvation insuring naked analyte to be detected, would result in increase signal to noise ratio signals and should account for the observation of signals that are hampered by the presence of this noise. Regarding MALDI-IMS two current and main limitations are encountered: the spatial resolution of the technology and its ability to be enough sensitive to detect biomolecules of lowest abundance. Many efforts were given to spatial resolution in the past years by use of more focused laser beam allowing decreasing up to ~50 µm resolution systems. Ideally, MALDI-IMS should provide 1 µm spatially resolved image to reach sub-cellular level imaging. Focusing laser beam up to 1 µm is achievable but main limitation is encountered in the ion formation. Previous fundamental studies clearly demonstrate the drastic decrease in the ion yield under laser focusing of 40-50 µm. On the other side, decreasing sensitivity threshold for observing lowly abundance can be slightly tuned by modifications of sample preparation including search for new matrices or developing specific sample treatments. However, a real break down in the limits could only be obtained by better understanding of the desorption/ionization process itself. By stating, on two different aspects comprising the existence of matrix/analyte clusters in MALDI that only desolvate progressively and a possible improvement of ion formation using different systems. We propose to increase ion yield by at least a factor 5 and find system to control cluster desolvatation and use this to improve MALDI-IMS performances for highly resolved MALDI-IMS (<10 µm). Final goal would be by increasing MALDI-IMS resolution for performing imaging system to equip clinical area.