From the titration curve of oleic acid by 0.10% wt NaOH and titration curve of waste vegetable by 0.10% wt NaOH it can be see that the buffer region which mean the amount of strong base added is still not enough to neutralize completely the weak acid in the range pH8.06-9.20 and pH7.78-8.00, respectively. Equivalence point which mean all of the acid has been converted to its conjugate base on the point pH=10.5 and pH=8.93, respectively. Strong base region which mean strong base is added further to the solution after equivalence point in the range pH12.18-12.85 and pH11.39-12.24.