The characterization of pharmaceutical powders by means of the SeDeM diagram expert system allows developing a database. This database is a useful tool in pre-formulation steps as initial screening for suitable filler excipients. This study compiles the characterization of 21 powdery Microcrystalline Celluloses (MCC) of different grades (101, 102, 301, 302 and 200) made by four different manufacturers (FMC Biopolymer, Ming Thai Co., Blanver, and JRS Pharma). The SeDeM characterization led to describing and to analysing the differences between each MCC studied. From this characterization, five Incidence means (Dimensions, Compressibility, Flowability, Lubricity/Stability and Lubricity/Dosage) and the Index of Good Compression (IGC) are calculated. If the IGC is below 5, the SeDeM diagram indicates that the powdery substance is not suitable for direct compression technology. The results show that each manufacturer has its own differences between grades: whereas JRS and FMC Biopolymer have well defined differences for each grade, there are no differences between grades 101 and 102 for Ming Thai products; and Blanver's grade 102 is less suitable for direct compression than grade 101. Then, each MCC is compared against the others of the same grade. Although they are usually described by the manufacturers similarly, the results indicate that there may be large differences between them. Finally, the different brands are compared from an overall perspective. The IGC averages for FMC Biopolymer and JRS are acceptable values (above 5). However, Blanver and Ming Thai present deficient values (below 5), though they are still close to the acceptance limit. Thus, it is possible to conclude that the products of JRS and FMC Biopolymer meet the manufacturers' description and seem to be more suitable (higher IGCs) for direct compression than those of Blanver and Ming Thai. (C) 2018 Published by Elsevier B.V.