We synthesize cobalt ferrite nanoparticles capped with an ultrathin phosphate layer of ∼ 1 nm thick by co-precipitation followed by hetero condensation of free surface OH- groups of orthophosphoric acid on CoFe2O4 particles. The synthesized phosphate capped CoFe2O4 nanoparticles (CFP) are characterized using X-ray diffractometer (XRD), simultaneous thermogravimetric analyser with differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), Vibrating sample magnetometer, Dynamic light scattering, Transmission electron microscopy and Energy dispersive X ray spectroscopy. XRD results confirm the formation of CoFe2O4 nanoparticles and the signature of POM stretching vibrations at 900 – 1200 cm−1 seen in FTIR spectrum confirm the surface bound phosphate moieties. The prevalent adsorption of water molecules through hydrogen bonding with PO43- moieties capped on CoFe2O4 nanoparticles made them hydrophilic in nature. The adsorption of different dyes on these particles is studied systematically. The phosphate moieties over cobalt ferrite greatly enhanced the adsorption of methylene blue where the adsorption efficiency and adsorption capacity were ∼ 89.5 % and ∼ 4.5 mg. g−1 respectively within 5 min. of incubation, as compared to nearly zero adsorption of methylene blue on uncoated CoFe2O4. On the other hand, the adsorption efficiency and capacity of brilliant blue R, bromo phenol blue and rhodamine B on CFP was very low. These results show that the adsorption of dye molecules over these particles depends on the nature of interactions between their functional moieties. The modes of interaction and influence of different functional moieties of dyes with phosphate moieties on CFP is studied and compared. As compared to the nonmagnetic nanoparticle based dye removal, the present approach is most suited for straight through channel dye removal without labor intensive steps such as centrifugation, precipitation and filtration.