The majority of capsule shells until 2014 are still made from gelatin from pork skin and bones. To overcome this problem, research on vegetable capsule shells began to develop based on seaweed extracts such as carrageenan, alginate, HPMC, and pectin. Existing vegetable capsule shells need to be upgraded to be more robust with the addition of polyhydroxybutyrate (PHB). Spirulina platensis microalgae is a PHB producer that is easy to cultivate, its production can be optimized by modifying the isolation method. Chemical disruption is the most simple and economical cell disruption method. It is followed with isolation steps of PHB precipitation and PHB purification. Sodium hypochlorite (NaClO) is a cell-disrupting solvent that is widely used for isolation of PHB from microalgae while sodium hydroxide (NaOH) has been used to isolate PHB from bacteria. The independent parameter tested in this study is the ratio of NaClO and NaOH used for cell disruption solvent ranging from 100:0, 85:15, and 75:25. The PHB quantification method used was FTIR, while for characterization is by calculating the PHB mass and extraction yield. The expected results of this PHB extraction is to get maximum yield of PHB and the most efficient extraction method based on the cell disruption solvent composition. Extraction of microalgae sample with 100:0 ratio of NaClO:NaOH is expected to have the highest yield of PHB compared to other variations.