The aim of this work was to propose and optimize the procedure for the determination of antimony by electrothermal atomic absorption spectrometry in reference materials of soils (S-VM no. 12-1-07 Eutric Cambisols; S-MS no. 12-1-08 Orthic Luvisols; and S-SP no. 12-1-09 Rendzina). The soils were decomposed using a mixture of concentrated HF and HNO₃ (1:1) under pressure. The determinations of antimony without modifier or in the presence of palladium nitrate as matrix modifier using atomization on the wall of the pyrocoated graphite tubes were compared using the peak area and peak height for evaluation. The obtained results were in good agreement with the certified values only when palladium nitrate and peak height were used.