tPolygalacturonase and pectinase activities reported in the literature were measured by several differ-ent procedures. These procedures do not give comparable results, partly owing to the complexity of thesubstrates involved. This work was aimed at developing consistent and efficient assays for polygalacturo-nase and pectinase activities, using polygalacturonic acid and citrus pectin, respectively, as the substrate.Different enzyme mixtures produced by Aspergillus niger and Trichoderma reesei with different inducingcarbon sources were used for the method development. A series of experiments were conducted to eval-uate the incubation time, substrate concentration, and enzyme dilution. Accordingly, for both assays therecommended (optimal) hydrolysis time is 30 min and substrate concentration is 5 g/L. For polygalactu-ronase, the sample should be adjusted to have 0.3–0.8 U/mL polygalacturonase activity, because in thisrange the assay outcomes were consistent (independent of dilution factors). Such a range did not existfor the pectinase assay. The recommended procedure is to assay the sample at multiple (at least 2) dilu-tion factors and determine, by linear interpolation, the dilution factor that would release reducing sugarequivalent to 0.4 g/L d-galacturonic acid, and then calculate the activity of the sample accordingly (dilu-tion factor × 0.687 U/mL). Validation experiments showed consistent results using these assays. Effectsof substrate preparation methods were also examined.