The equilibrium moisture contents for skim milk powder at temperatures between 55degreesC and 90degreesC and for relative humidities between 3.3% and 19% have been measured in order to assess the drying behaviour of this material in spray dryers, where these temperature and relative humidity conditions are common. Several literature correlations have been tested, the formula proposed by Papadakis giving the best fit in this range. (C) 2002 Elsevier Science Ltd. All rights reserved.