Aim: The purpose of this study was to evaluate the cleaning effectiveness of kedo-S Square pediatric rotary files versus hand K-files systems on extracted primary molars. Material and method: In this experimental study, 44 roots of 22 extracted primary mandibular molars with at least two-thirds of intact roots were selected. After access cavity preparation, the canals were injected with India ink with an insulin syringe. The roots were randomly assigned into two groups: group I (n= 22): Manual k-files and group II (n = 22): Rotary kedo-S Square files. Each group was instrumented with the respective files. After instrumentation, teeth were decalcified, dehydrated, cleared, and analyzed for the presence of India ink remaining on the root canal walls, which served as evidence of the cleaning capacity of both files. Result: Kedo-S Square rotary files performed significantly better cleaning of the canals in the coronal third than K-file (P = 0.012). While, in the middle and apical third of the root, the difference between the two groups was not significant (P=0.169) and (P=0.236) respectively. Conclusion: Kedo-S Square pediatric rotary system showed significantly better cleaning than K-files in the instrumentation of primary molars root canals.