An analytical method, based on separation by pyrohydrolysis and quantification by ion chromatography for the simultaneous trace level determination of B, Cl, F and Mo in U₃Si₂ was proposed. The optimum pyrohydrolysis conditions were identified and a two-step isocratic ion chromatography procedure was proposed for their sensitive determination. The developed method was validated by comparing the results obtained for B and Mo by spectrophotometry and ICP-AES, respectively, whereas an in-house working standard of UO₂ was used for F and Cl. The method limit of detection was 0.5–0.6 μg g⁻¹ for B, F and Cl and 2.5 μg g⁻¹ for Mo.