Abstract: A method for the determination of the amount of mercury in an electrolyticcell by means of isotopic dilution with ~(197)Hg containing ~(197)Hg and ~(203)Hg is descri-bed. To check the accuracy of the method, accurately weighed amount of Hg isadded to the cell and the amount redetermined, and it is found that the error iswithin±0.3%. This method is not only more convenient to use, but is also muchmore accurate than the old method of weighing the Hg that has to be emptiedfrom the cell.