This Technical Report describes an inductively coupled plasma optical emission spectrometric method for the determination of Al, Ti and P contents in ferro-silicon materials. The method is applicable to: - Al contents between 0,2 and 2 %; - Ti contents between 0,02 and 0,25 %; - P contents between 0,005 and 0,05 %. The procedure is valid for the analytical lines given in Table 1. This table also gives, for each line, the spectral interferences, which shall be corrected. NOTE The interferences extent as well as other possible interferences depend on the temperature in the plasma and on the optical resolution of the spectrometer used.