Temperature is an important characteristic in electric arc discharge processes for physical vapor deposition treatments. In this work, a titanium cathode was used and, by identifying the spectral emission lines in the range 300 nm−550 nm, it was possible to determine by means of the Boltzmann graphical method the temperature of the plasma generated in specific areas of the cathode surface during the discharge process of Arc. As a result, the estimated temperature has close values for the different emission lines (T i+, T i++, and T i+++) with uncertainties lower than 10%.