Magic-angle spinning phosphorus NMR spectra have been used to analyze the adsorption of an organophosphate and an organophosphonate into the pore structure of SC2 nutshell carbon. The adsorption process was found to be almost identical for each of the materials and in both cases continued within smaller pores for over 24 h. At high quantities of added phosphate or phosphonate, the amount of material actually adsorbed increases, and this is shown to be a result of pore expansion. Sequential adsorption of the two phosphorus-containing molecules was also studied. Upon addition of the second adsorbate, quick displacement of the initially adsorbed material is observed from within the pores. This is followed by a slow entry into the pores by both materials while the porous volume increases significantly. The amount of each adsorbate material within the pores is found to depend on the order of addition of the two organophosphorus materials, possibly due to a "pore-blocking" mechanism.