Moisture sorption isotherms of five commercial black bean varieties harvested in the province of Salta, Argentina, were measured. Statistical methodology was applied to compare their sorption characteristics and it was observed that the five varieties could be considered as belonging to a same group. Different equations proposed in the literature were studied and it was found that the best adjustments were provided by the Oswin and the White and Eiring equations. The estimated isotherm equations are given. Adjusting the equations to sorption data found in literature, the White and Eiring equation provided a reasonable adjustment for all of them. (C) 2003 Elsevier Ltd. All rights reserved.