Fermentation process by Acetobacter sp.RMG-1 using coconut water or pineapple extract as medium yields acetic acid and cellulose. Total concentration of acetic acid obtained was 2,23 mg/ml in the fermentation performed for 168 hours using coconut water and 8,35 mg/ml in the fermentation performed for 96 hours using pineapple extract. The highest acetic acid concentration of 24,79 mg/ml in the fermentation using coconut water was reached after 96 hours, while in the fermentation using pineapple extract the highest acetic acid concentration of 4,41 mg/ml was reached after 24 hours. The average production of cellulose in the coconut water medium was 10,02 gram (wet) or equivalent to 1,95 gram dry weight, while in the pineapple extract medium was 11,32 gram (wet) or 2,24 gram dry weight. The results of this work showed that acetic acid concentration in coconut water fermentation was higher than in the pineapple extract medium, but cellulose production was higher in pineapple extract medium.