A method for determination of residual oxygen in sealed pharmaceutical glass vials was developed and validated using gas chromatograph (GC) with thermal conductivity detector (TCD). The gas in the headspace of the vial is collected in a gas tight syringe and injected to GC maintained at 35°C using a molecular sieve packed column and helium as carrier gas. The GC conditions were maintained to separate oxygen from other interference thus to obtain a well resolved peaks. Known amount of sample and reference standard are injected through gas tight syringe and the concentration of residual oxygen present in the headspace of sample is quantitatively measured.