CoFe2O4 and CoFe1.9Bi0.1O4 nanoparticles are prepared by combustion method utilizing glycine. Pure phase formation is affirmed from the X-ray diffraction and Fourier transform infrared spectroscopy. From the Scanning electron microscopy and Energy Dispersive X-ray spectroscopy, morphology and presence of respective elements in the synthesized compounds are analyzed. Decrease in average crystallite size and increase in lattice parameter is observed due to bismuth substitution. The adsorption capability of CoFe2O4 and CoFe1.9Bi0.1O4 are tested for one of the toxic environmental pollutants chromium (VI). The adsorption efficiency with respect to adsorbent quantity, concentrations of adsorbate and pH are studied. The substitution of the bismuth increased the adsorption capability of cobalt ferrite nanoparticles. © Published under licence by IOP Publishing Ltd.