Abstract: Sample of sulfur was digested with nitric acid using microwave digestion method. The content of Fe in the sample solution was determined by GF-AAS. Solution of 1 g·L-1 magnesium nitrate (10 μL) was used as matrix modifier. The ashing temperature was 1 200 ℃ and the atomization temperature was 2 000 ℃. Linear relationship between values of absorbance and mass concentration of Fe was kept in the range of 3.0-25.0 μg·L-1, with detection limit (3s/k) of 0.5 μg·L-1. Precision of the method was tested at the sample of industrial sulfur, value of RSD (n=6) found was 2.2%. Test for recovery was performed by standard addition method, giving recovery in the range of 99.5%-101%.