This study aimed to assess the antioxidant activity and total phenolic content of twelve seaweed species collected from the Jarjar Oma coastline. All evaluated extracts demonstrated notable antioxidant properties, showing their potential use in pharmaceutical applications and the food industry. The antioxidant capacity varied significantly among species, showing a strong species-specific influence. The green alga Cladophora glomerata exhibited the highest antioxidant activity followed by Acetabularia acetabulum and Oedogonium grande, further supporting the trend that green algae generally show stronger antioxidant properties compared to brown or red algae. In contrast, brown algae such as Cystoseira barbata, Padina pavonica, and Dictyota dichotoma demonstrated the lowest antioxidant activities, possibly due to seasonal variation, extraction methods, or differences in phenolic compound composition. Red algae, including Laurencia papillosa and Polysiphonia lanosa, exhibited moderate antioxidant activity. The study also revealed significant variation in total phenolic content among the seaweed species. The highest phenolic content was observed in the green alga Oedogonium grande, followed Cladophora glomerata. Brown algae such as Cystoseira crinita, C. compressa, and C. barbata showed moderate phenolic levels, consistent with their known richness in phlorotannins. In contrast, red algae like Jania rubens and Polysiphonia lanosa exhibited the lowest phenolic contents. These results indicate that the phenolic content and antioxidant activity of seaweeds are strongly influenced by their taxonomic classification, ecological habitat, and surrounding environmental factors..................... Keywords: ............Seaweed, Total Phenolic Content, Antioxidant capacity, Jarjar oma coast.