10.22376/ijpbs.2019.10.1.p1-12 Volume 4 Issue 4 2013 (October - December) This study aimed to obtain optimum operating conditions in the production of cellulase by Response Surface Methodology using lessThan i greaterThan Bacillus sp. lessThan /i greaterThan BPPT CC RK 2. This optimization used natural substrate that was cheap and widely available in Indonesia. This substance was also a source of carbon and nitrogen for the production of cellulose enzymes. These carbon and nitrogen sources are the emerging substance to replace carboxylmethyl (carbon source) and yeast extract (source of nitrogen) that are still expensive. The research was conducted in four stages, namely: (1) the manufacture and the selection of medium composition ; (2)enzyme production through fermentation; (3) the use of Response Surface Methodology using a software design expert in determining the optimum point of cellulase; (4) and the enzyme activity test. The results showed that the isolates lessThan i greaterThan Bacillus lessThan /i greaterThan lessThan i greaterThan sp lessThan /i greaterThan . CC BPPT optimum RK 2 produce cellulase for 12 hours in media with concentrations of rice bran 50% (w/v), and coconut water concentration of 20% (v/v). MISRI GOZAN, AGUNG MARSSADA BIORATA AND SISWA SETYAHADI Optimization, Cellulase, Bacillus sp.,Response surface methodology, Fermentation time 1063-1070