Pellets are spherical agglomerated particles used to produce multiparticulate pharmaceutical dosage forms. This study aims to develop a new approach that evaluates the deformation behavior of pellets under compression, by combining tableting data and compression models with X-ray micro computed tomography (XMT) image analysis. The deformation of Microcrystalline cellulose (MCC) and sugar pellets known to have different deformation behavior under compression was investigated. Compression data and modeling confirmed the plastic and brittle behavior for MCC and sugar pellets respectively. Image analysis of the XMT showed a different evolution of the morphometric parameters: structure thickness diameter (St Th) and volume equivalent sphere diameter (ESDv). The brittle sugar pellets showed a decrease in both ESDv and St Th parameters while plastic MCC pellets showed a decrease in ST Th and a constant ESDv which is coherent with ductile and brittle material deformation. This study shows that XMT can be used as a tool to characterize the mechanical behavior of pellet particles during compression