Abstract: A method for the determination of platinum content in CO combustion improver using a spectrophotomeic method is described.In an HC1 medium, Pt(Ⅳ)was reduced by SnC1₂ solution and formed a yellow color chloroplatious acid(H₂PtC1₄).The absorption maxima of which is at a wavelength of 403 nm.The method features simplicity,rapidness and accuracy,with a recovery in the range of 97% to 103%,and the relative standard deviations were less than 2%.The common elements existed in the CO combustion improver do not interfere the determination of platinum under the optimized test conditions.