SUMMARYInfrared absorption spectra of phosphate sorbed on alumina gel were obtained by subtracting the diffuse reflectance infrared (DRIR) spectra of alumina gel from those of phosphated alumina gel. The positions of the absorption bands due to P·O stretching vibration were little affected by the change in pH and the amount of phosphate sorbed. These absorption bands were similar to those for aluminium phosphate gel. The sorption product of phosphate on alumina gel was amorphous by X‐ray diffraction. Na+and Cl−adsorption properties of alumina gel tended towards those of aluminium phosphate gel with phosphate sorption. It was concluded that the state of phosphate sorbed on alumina gel is similar to that of aluminium phosphate