An efficient and selective porous nanostructured polymer adsorbent is prepared from smectic liquid crystals. The adsorption study is performed by using hydrophilic dyes as water pollutants. The anionic pore interior of the nanoporous polymer is able to selectively adsorb cationic methylene blue over anionic methyl orange. Even zwitter ionic rhodamine B could hardly be adsorbed due to the presence of the anionic group in this dye. The confined pore dimensions allow size selective adsorption; a 4th generation cationic dendrimer is not able to diffuse into the nanometer sized pores. The porous nature of the polymer provides easy and fast accessibility of all adsorption sites. Stoichiometric ion exchange is obtained, which equates to an adsorption capacity of nearly 1 gram of methylene blue per 1 gram adsorbent. A competitive Langmuir adsorption constant and pseudo second order rate constant are determined. The adsorbent and adsorbate could both be retrieved after acid treatment of the polymer.