Transformasi gen superoxide dismutase (MaSOD) pada rumput laut Kappaphycus alvarezii menggunakan Agrobacterium tumefacient telah dilakukan secara in vitro. Transformasi gen MaSOD ke dalam genom rumput laut diharapkan dapat mengurangi cekaman oksidatif terutama yang disebabkan oleh perubahan suhu, salinitas, dan cemaran logam di perairan. Penelitian ini bertujuan untuk regenerasi rumput laut hasil introduksi gen MaSOD dan non-transgenik pada labu kultur. Regenerasi dan perbanyakan rumput laut hasil transformasi gen MaSOD dilakukan di laboratorium pada labu kultur yang diletakkan dalam “culture chamber” yang dilengkapi dengan aerasi menggunakan media kultur yang diperkaya dengan pupuk PES, Grund, Conwy, dan SSW sebagai kontrol, salinitas 20, 25, 30, 35, dan 40 g/L, pH 4, 5, 6, 7, dan 8. Intensitas cahaya antara 500-2.000 lux dengan fotoperiode terang dan gelap 8:16; 12:12; dan 16:8. Untuk merangsang pertumbuhan eksplan dilakukan pemeliharaan dengan penambahan hormon tumbuh IAA dan BAP dengan perbandingan 1:1, 1:2, dan 2:1. Penelitian dilakukan secara bertahap. Evaluasi transgenik dilakukan menggunakan teknik PCR. Hasil penelitian memperlihatkan bahwa sintasan yang paling tinggi diperoleh menggunakan media PES (94%), salinitas 30 g/L (90%), pH 7 (96%), intensitas cahaya pada 1.500 lux (80%), fotoperiode 12:12 (84%), komposisi ZPT dengan campuran IAA dan BAP dengan perbandingan 2:1. Hasil analisis PCR memperlihatkan K. alvarezii transgenik putatif mengandung transgen MaSOD sebanyak 78% dari hasil transformasi.Superoxide dismutase transformation (MaSOD) gene of seaweed Kappaphycus alvarezii mediated by Agrobacterium tumefacient has been successfully done in vitro. MaSOD genes introduced into the seaweed genome is expected to reduce oxidative stress caused by environmental conditions such as changes in temperature, salinity and metal contamination of the water. This study aimed to regenerate both the MaSOD transformed seaweed and non-transgenic in a culture flask. Regeneration and multiplication of those seaweed were conducted in a laboratory flask cultures placed in a “culture chamber” which was aerated and enriched with fertilizers PES, Grund, Conwy, and SSW as a control, salinity 20, 25, 30, 35, and 40 g/L, pH: 4, 5, 6, 7, and 8. the light intensity between 500-2000 lux, with light and dark photoperiod 8:16; 12:12; and 16:8. To stimulate the growth of explants the addition of growth hormone IAA and BAP with ratios of 1:1, 1:2 and 2:1 were performed. This study was a multiple-step of process, by which transgenic explants was identified by PCR method. The results showed that the highest survival rate was obtained using media PES (94%), salinity 30 g / L (90%), pH= 7 (96%), the intensity of light at 1500 lux (80%), photoperiod= 12: 12 (84%), and ratio of IAA and BAP 2: 1. The results of PCR analysis showed the putative K. alvarezii transgenic MaSOD was 78% of explants.