The seeds of Araucaria angustifolia, commonly known as pinhao, are widely consumed in both Southern and Southeastern Brazil due to their high nutritious value comprised basically by starch. The literature on the technological aspects of this seed is still very scarce. Moisture adsorption isotherms of pinhao starch were determined at 10, 20, 30 and 40 degrees C using the gravimetric method. Results show that the Peleg model most appropriately represents the experimental data. Other models (Chung-Pfost, GAB, Henderson, BET and Chirife) also were found to adjust well. The isosteric heat of sorption (differential enthalpy) was calculated by using the moisture adsorption isotherm and decreased as moisture content increased. The enthalpy-entropy compensation theory was applied to adsorption isotherms and the isokinetic temperature for pinhao starch was calculated by plotting the differential enthalpy versus differential entropy. It was found that the adsorption process investigated was enthalpy-controlled and spontaneous. (C) 2010 Elsevier Ltd. All rights reserved.