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The effects of phenological stages on the composition, antioxidant, insecticidal and allelopathic properties of essential oils (EOs) obtained from the aerial parts of Thymus maroccanus Ball. were evaluated. The GC-MS analysis identified that analyzed EOs were dominated by carvacrol (63.70 - 68.19 %) followed by p-cymene (6.09 - 9.67 %) and γ-terpinene (3.67 - 8.49 %). When carvacrol and p-cymene gradually increased from the lowest values (63.70% and 6.09%) at the pre-flowering stage to reach the highest ones (68.19% and 9.67%) at post-flowering stage, γ-terpinene gradually decreased from the highest proportion (8.49%) to the lowest (3.67%). EO from post-flowering aerial parts showed higher scavenging ability on DPPH radicals (% inhibition: 25.19 - 95.75 %; IC50 = 0.26 mg/mL), in contrast, the essential oil from pre-flowering stage exhibited the highest Fe³⁺ reducing power ability (Absorbance:  0.329 - 0.812; IC50 = 0.14 mg/mL). Insecticidal properties showed no substantial difference between T. maroccanus EO extracted at different growth stages. The LD50 and LD90 values were ranged from 0.15 to 0.17 µL/cm², and from 0.37 to 0.47 µL/cm², respectively in contact assays, as well as from 318.93 to 362.84 µL/L air, and from 725.08 to 739.12 µL/L air, respectively in fumigant assays. The results indicated that allelopathic activity of Eos is not greatly affected by growth developmental stages.