This paper aims at investigating the polarographic behavior of cadmium (II) and constructing a calibration chart using a manual polarography. Solutions containing different concentration of cadmium (II) were prepared and analyzed by polarographic method. From the collected data, the polarograms were drawn for each analyzed test solutions. From the polarograms, diffusion current (Id) was determined for each solutions and plotted against their concentrations. The plot resulted in a straight line and it shows the linearity of diffusion current with the concentration of the depolarizer ion. The value of half wave potential (E1/2) was also determined for all solutions and it was found to be uniform. The log-plot was drawn by taking log[I/(Id-I)] as ordinate and the potential applied as abscissa. All the log plots resulted in a straight line in strictly increasing interval and their slope values were determined and found to be approximately in the environs of theoretical value (29.6 mV). This shows the reversible reduction of the depolarizer.