Cyanex 921, a neutral extractant, has been used for the extraction of beryllium(rr) from basic media and employed for the separation of beryllium(II) in the presence of aluminum(III). Cyanex 921 diluted in cyclohexane extracted beryllium(II) in the 8.0-10.0 pH range and aluminum(III) between 4.5-5.5 pH. The selectivity of beryllium(II) over aluminum(III) was high in the 8.0-10.0 pH range. The extracted beryllium(II) was stripped with 0.5 M NaOH without any significant loss of the ligand while loaded aluminum(III) was stripped with 2 M HCl. The extractability of beryllium(II) and aluminum(III) was also studied separately as a function of pH, temperature, equilibration time, and stripping ability with NaOH, KOH, HCl, HNO3, H2SO4, and HClO4. Based on these results, a sequential method was developed for the separation of beryllium(II) from aluminum(III).