The water sorption isotherm of sponge cake at 20 °C was determined using DVS apparatus and saturated salts method. Results in adsorption are presented. Combining the saturated salt method with the DVS method afforded sufficient information to get a complete sorption curve. The adsorption curve increases sharply above the water activity value of 0.90 and the maximum moisture content of the sponge cake near saturation reaches 2.3 g/g d.b. Guinot and Mathlouthi (1990) have reported similar results at 20 °C for industrial sponge cake using the standard saturated salts method.