-A high dosage of albendazole (ABZ) is required for treating systemic helminthe infections because of its low solubility. Aiming at increasing ABZ solubility, complexation with beta-cyclodextrin ( -CD) using aqueous and acetic acid solutions as ABZ solubilizer was studied. In aqueous -CD, complexation increased solubility 53.4 times, giving a complex equilibrium constant of 1266 L mol -1 with a maximum ABZ concentration of 276 µmol L -1 for 16.3 mmol L -1 -CD. For complexation in 1.05 mol L -1 acetic acid, UV absorbance spectra and 1 H-NMR analysis confirmed complex formation. The UV absorbance of ABZ/acid acetic/ -CD solutions was modeled by the formation of two complexes with molar ratios 1:1 and 1:2 ABZ: -CD. When neutralized with NaOH these solutions did not form precipitates only for the ABZ: -CD molar ratios of 1:8 and 1:10, showing that ABZ solubility could be increased 306 times. Results show that high -CD molar ratios hold ABZ in solution by complexation enhanced by the acetate anion.