Hydrophobic apatite monolith nanoparticles were prepared by grafting of dodecylphosphate (DP) onto hydroxyapatite. A modification in the synthesis was used to develop a hydrophobic surface in order to improve the dispersion and compatibility of organoapatite particles for the sensing and separation of hydrophobic substances. Results indicate that DP grafting onto the apatite is quantitative. Structural analyses of the as-received materials show that the grafting approach did not significantly alter the apatite microstructure, but modifies the hydrophobic character and surface properties of the hybrid material. Conversion of the hydrophilic surface of hydroxyapatite to hydrophobic was carried out to better retain naphthalene as a polynuclear aromatic hydrocarbon model.