A trace level concentration of osmium(VIII) has been quantitatively extracted from 1.0 M hydrochloric acid with 0.087 M N-n-octylaniline as a stationery phase on silica gel. Osmium(VIII) has been eluted with 5.5 M, 25 mL hydrochloric acid and determined by spectrophotometric method. Various parameters influencing the extraction, such as acid concentration, reagent concentration and flow rate have also been studied to determine the optimum conditions for the quantitative separation of osmium(VIII). This method is free from large number of interferences from cations and anions. This method has been effectively applied for the separation of osmium(VIII) from neuyanskite and osmiridium alloy. Osmium(VIII) has also been separated from rhodium(III), ruthenium(III) and base metals such as iron(II), copper(II) and lead(II). The method is found to be simple, rapid and reproducible.