Abstract: Background and Objective: Bakasang is a typical food of North Sulawesi and its surroundings, made from fermented fish viscera. This food is made by fermentation so that it is rich in amino acids and polypeptides. This study aimed to determine the optimum processing conditions for Bakasang with Peroxide Value (PV) parameters based on Response Surface Methodology (RSM) with Central Composite Design (CCD). Materials and Methods: Viscera from fresh Skipjack tuna consisting of intestines, liver, heart and eggs were mixed with salt and left in a fermenter for varying times and temperatures to obtain Bakasang. The fermentation temperature, salt content, and fermentation time, determined based on the Central Composite Design (CCD), were variables in this study. Thus, 20 experiments consisted of eight quadratic points, six centre points and six axial points. Results: The results showed that the correlation test between temperature, salinity and fermentation time variables on PV were 0.521, 0.305 and 0.591. The regression test resulted in an R2 value of 0.988. The model equation obtained was y = 4.35194 - 0.11363x1 - 0.07459x2 - 0.25300x3 + 0.00157x12 + 0.00310x22 + 0.01571x32 - 0.00064x1x2 + 0.00172x1x3 + 0.00340x2x3. The contour plot graph obtained from the experiment using CCD showed that the optimum processing conditions for Bakasang were at a temperature of 32.9324°C, salinity 10.2631% and fermentation time of 4.7793 days, which will produce Bakasang with an optimum PV of 1.51256 meq kg–1 sample. Conclusion: According to the findings of this study, the optimum temperature, salinity and fermentation time for producing Bakasang with a PV of 1.51256 meq kg–1 sample were 32.932°C, 10.263% and 4.779 days, respectively.