Chicken “isaw,” which is common street food in the Philippines, is prepared by conventional frying and is observed to have poor shelf-life and keeping qualities. Hence, a new product was developed employing vacuum frying technology to minimize undesirable changes and provide longer shelf-life as the conditions under vacuum frying involves the use of low temperature and minimal exposure to oxygen. However, data on its quality is not yet available since the product is new. Thus, the development of sorption isotherm and understanding of isosteric heat of sorption to the newly developed product is essential for the quantitative approach to predicting stability and quality changes during packaging and storage. Isotherms of vacuum fried chicken “isaw” were measured at 20 °C, 30 °C, and 40 °C by the static gravimetric method over a range of relative humidity (RH) from 7–75%. BET (up to 43% Aw), Smith, Kuhn, Oswin, Karel, and Peleg were the mathematical models used in fitting the experimental sorption data. Corresponding to BET, the monolayer moisture content (Xm) revealed that the vacuum fried chicken “isaw” must have a moisture content of 3.79%, 1.98%, and 1.96% at 20 °C, 30 °C, and 40 °C, respectively to prevent auto-oxidation and to enhance product stability of vacuum fried chicken “isaw” during storage. The net isosteric heat was calculated using the Clausius-Clapeyron equation and was observed that as moisture content is decreased, the isosteric heat of sorption increases. With these data gathered, generating and understanding the product’s sorption isotherm, energy constants, and general equation at 20 °C, 30 °C, and 40 °C would provide valuable information for predicting quality changes during storage and packaging and for convenience in its future processing in an attempt to improve its quality, safety, and profitability.