In this experiment we used the process ofcoulometric titration which is one branch of Coulomb's Mate technique to measure electrical charges (electrons) .The sample in this experiment is two analyte is HCl and KCl . First of all, we make prepare sample solution.Before titration we put 5 drop of phenolthalein into HCl and put a magnetic bar in HCl and used to salt bridge for connect HCl with KCl because phenolthalein is an indicator. In part of standardization, we titrate solution until HCl change to pink color. Including, part of determination of concentration H+in HCl , we titrate the sample until it change color.