A method is proposed for determination of surface compounds containing nitrogen incorporated into activated carbon and other carbon adsorbents. The method is based on the redox reaction between hydrochloric acid and the surface compounds. Materials obtained by treating activated carbon with concentrated nitric acid or hydrogen peroxide as well as by passing nitric oxide through the carbon and by thermal treatment of samples pretreated with nitric acid were investigated. It was established that the redox reaction on which the method is based proceeds only in the presence of surface groups containing both nitrogen and oxygen. I.r. spectroscopy and XPS showed that organic nitrates and nitrate complexes containing NO3- can be determined by the method.