Polymeric materials, especially those of spherical in shape, have been utilized in numerous applications for decades. Numerous polymerization techniques are used to obtain polymeric sorbents with different grain sizes. Polymers in the form of porous or non-porous microspheres we can obtain by one of the heterogeneous polymerization: emulsion, suspension dispersion polymerization, membrane emulsification, or swelling and polymerization techniques. The obtained materials can be used in solid-phase extraction for the isolation of organic compounds from water and air, and as stationary phases in high performance liquid, supercritical fluid, ion-exchange and size-exclusion chromatography [1, 2]. For certain applications, polymer materials are chemically modified. For this purpose, functional groups or unreacted double bonds present in the polymer structure are used. Carbonization is one method which enables the generation of polymer microspheres with carbonaceous surface. However, polymers often undergo sintering or shrinking during carbonization. This has an unfavourable influence on the porous structure and causes that the material to become microporous and lose its sorption properties. For this reason, to improve sorption properties of carbonized sorbents, various pretreatment methods are employed. Our experience shows that modification with phosphoric acid is an effective method [3,4].