In this study, the effect of debittering methods (normal water, brine, oak ash and NaOH) on the phenolic compounds and sensory properties of olives in the production of pickled olives was investigated. The hydroxytyrosol contents of the control group olives of Ayvalık and Gemlik olives were determined as 92.37 and 67.73 mg/100 g, respectively. The hydroxytyrosol contents of scratched fermented “Ayvalık” olives debittered in normal water, brine, oak ash and NaOH were detected between 30.49 (0.day) to 58.0 mg/100 g (30.day), 24.41 (10.day) to 80.43 mg/100 g (0.day), 37.75 (45.day) to 94.51 mg/100 g (60.day) and 17.52 810.day) to 27.49 mg/100 g (30.day). In addition, hydroxytyrosol amounts of crushed fermented “Ayvalık” olives according to the same bitterness removal order were identified between 45.53 (60.day) to 89.15 mg/100 g (30.day), 41.85 (10.day) to 117.71 mg/100 g (45.day), 33.15 (10.day) to 71.30 mg/100 g (45.day) and 17.36 (0.day) to 25.90 mg/100 g (10.day), respectively. The oleuropein contents of the control groups of “Ayvalık” and “Gemlik” olive cultivars were determined as 108.33 mg/100 g and 81.81 mg/100 g, respectively. In addition, oleuropein contents of whole fermented “Ayvalık” olives changed between 54.61 (60.day) and 55.42 mg/100 g (45.day), 55.35 (30.day) and 55.67 mg/100 g (60.day), 55.07 (10.day). and 55.59 mg/100 g (30.day) and 14.97 (0.day) to 18.14 mg/100 g (10.day). The highest decreasing components were hydroxytyrosol, tyrosol, caffeic acid and oleuropein. In general, the phenolic content of olives on the 0th day of fermentation was slightly higher than the other days of fermentation. In general, the sensory properties of whole, scratched and crushed “Ayvalı” and “Gemlik” olives on the 45th day of fermentation were most appreciated by the panelists. In addition, the sensory values of all olives treated with NaOH were not appreciated by the panelists.